420 4.2.0 RESOLVER.ADR.Ambiguous; ambiguous address

Posted on Leave a commentPosted in active directory, exchange, exchange online, Exchange Server, migration, smtp

This error can turn up in Exchange Server when Exchange Server is trying to resolve the object that it should deliver a message to. Exchange queries Active Directory and expect that if the object exists in the directory, that the object exists only once. If the object exists more than once, this is the error – as Exchange does not know who to deliver the email to.

The error is visible when running Get-Queue in Exchange Management Shell, and seeing that there are lots of emails in the Submission Queue. If you run Get-Message –Queue servername\Submission | FT Identity,FromAddress you can pick one to look at, and for that one run Get-Message server\submission\ID | FL where server\submission\ID is the Identity value from Get-Message cmdlet. Here you will see LastError and Recipients showing the ambiguous address error.

There are a number of articles on the internet covering this issue, but I came across a unique one today.

The easy way to search for the issue is to find the address that is in duplicate. This will be listed in Event Viewer under MSExchangeTransport as the source and Event ID 9217. The Task Category will be Categorizer, as the job of working out who is going to get the message is the role of the Categorizer.


An example of this error is shown.

So the fix. Often suggested is to do a custom AD query for “proxyaddress=smtp:name@domain.com” where name@domain.com is the email address shown in the event log error. If this returns two or more recipients, and this will be across all the domains in the forest, then you need to decide which is the primary one and carefully delete the rest.

By carefully I mean that you want to leave either one contact, or one mail user or one mailbox etc. If the duplicate is two contacts, then find the one with the most correct information on it and carefully delete the other. If you find two mailboxes, work out which the user is actually logging into and has email in it – and carefully delete the other etc.

And by carefully, here I also mean that on the object you are going to delete, copy the legacyExchangeDN value and then delete the object. Then find the real correct object and add a new x500 email address to the proxyAddresses attribute of the correct user. The value of the x500 address will be the legacyExchangeDN that you copied from the deleted contact.

This will ensure that users who have previously emailed the now deleted contact before, will still be able to email the remaining object.

But what is unique about that? At the customer I am working on at the moment the issue was that doing the proxyaddresses=smtp:name@domain.com search only returned one object across the entire forest – what is duplicate about that? Well in my case, the user had user@domain.com added to their proxyaddresses twice – they were the duplicate object to themselves.


Opening this user via the search results as shown above, and with Advanced Features enabled from the View menu, you can see the Object tab:


Opening the object value directly, redacted in the picture above, I can change to the Attribute Editor tab and open proxyAddresses attribute. Here i saw the following:


name@mail.domain.com (used as a target for forwarding emails from another system)



x500:legacyExchangeDN from Exchange 2007 migration

Note that the name@domain.com value, the one in error in the logs, appears twice but not starting SMTP (primary address) or smtp (secondary address) but without an address protocol at all!

Querying the user in Exchange Administration Console returned:


And also then opening the user in Exchange Management Console showed that the address without the smtp: value was shown with it.

Remove one of the two addresses and within ten minutes the emails queued to this user in the submission queue will be delivered. Restarting the transport service will also kick start the submission queue as you cannot use Retry-Queue against this queue.

Exchange Online Migration Batches–How Long Do They Exist For

Posted on 3 CommentsPosted in exchange, exchange online, Exchange Server, hybrid, microsoft, migration, Office 365

When you create a migration batch in Exchange Online, the default setting for a migration is to start the batch immediately and complete manually. So how long can you leave this batch before you need to complete it?

As you can see from the below screenshot, the migration batch here was created on Feb 19th, which was only yesterday as I write this blog.


The batch was created on the morning of the 19th Feb, and set to manual start (rather than the default of automatic start, as did not want to migrate lots of data during the business day) and then it was started close to 5:30pm that evening. By 11:25pm the batch had completed its initial sync of all 28 mailboxes and there were no failures. There were other batches syncing at the same time, so this is not indicative of any expected or determined migration performance speeds.

So what happens next. In the background a new mailbox move request was created for each mailbox in the batch, and each individual mailbox was synced to Exchange Online and associated with the synced Mail User object created in the cloud by the AADSync process. When each move reached 95% complete, the move was suspended. It will be resumed around 24 hours later, so that each mailbox is kept up to date once a day automatically.

If you leave the migration running but not completed you will see from the migration batch status above that the batch will complete in 7,981 years (on the 31st Dec 9999 and one second before the next millennium bug hits). In the meantime the migration batch sync will stop doing its daily updates after two months.

After two months of syncing to the cloud and not being completed, Exchange Online assumes you are still no closer to migrating and they stop keeping the mailbox on-premise and the mailbox in the cloud in sync. You can restart this process by interacting with the migration batch before this time, or if it does stop by just clicking the Resume icon, and this will restart it for a further period of time.

Outbound Email Via Exchange Online Protection When Using Hybrid Exchange Online

Posted on 1 CommentPosted in dmarc, EOP, exchange, exchange online, Exchange Online Protection, Exchange Server, hybrid, mailbox, spf

In a long term hybrid scenario, where you have Exchange Online and Exchange Server configured and mailboxes on both, internet bound email from your on-premises servers can route in two general ways.

The first is outbound via whatever you had in place before you moved to Office 365. You might have configured Exchange Online to also route via this as well.

The second is to route Exchange Server outbound emails via Exchange Online Protection. Your Exchange Online configuration does not need to be adjusted for this to work, as the default route for all domains to the internet (or the * address space as it is known) is via EOP as long as you create no alternative outbound connector for *.

This blog post looks at configuring Exchange Server so that your on-premises mailboxes also route out via Exchange Online Protection, and does it without changing the connectors made by the hybrid wizard. If you change the hybrid wizard connectors and then run the wizard again, it will reset things to how it wants them to be, which will remove your configuration changes.

This configuration setup results in a single new send connector created on-premises in Exchange Server (or one connector per site is you route emails from more than one Active Directory site). This new connector is not the Outbound to Office 365 connector that the hybrid wizard creates and so changes here do not break hybrid and changes to the hybrid wizard do not impact outbound mail flow.

This blog post also assumes you already have a working route outbound for all internet emails and you are swapping over to outbound via EOP, so these steps work though ensuring that is correct and will work before changing the route for *.

Examine the hybrid send connector to Office 365

[PS] C:\ExchangeScripts\pfToO365>Get-SendConnector out* | fl

AddressSpaces:                  {smtp:domainuk.mail.onmicrosoft.com;1}
AuthenticationCredential :
CloudServicesMailEnabled :      True
Comment : ConnectedDomains :    {}
ConnectionInactivityTimeOut :   00:10:00
DNSRoutingEnabled :             True
DomainSecureEnabled :           False
Enabled :                       True
ErrorPolicies :                 Default
ForceHELO :                     False
Fqdn :                          mail.domain.uk
FrontendProxyEnabled : 	        False
HomeMTA :                       Microsoft MTA
HomeMtaServerId :               SERVER01
Identity :                      Outbound to Office 365
IgnoreSTARTTLS :                False
IsScopedConnector :             False
IsSmtpConnector :               True
MaxMessageSize :                35 MB (36,700,160 bytes)
Name :                          Outbound to Office 365
Port :                          25
ProtocolLoggingLevel :          None
RequireOorg :                   False
RequireTLS :                    True
SmartHostAuthMechanism :        None
SmartHosts :                    {}
SmartHostsString :
SmtpMaxMessagesPerConnection :  20
SourceIPAddress :     
SourceRoutingGroup :            Exchange Routing Group (DWBGZMFD01QNBJR)
SourceTransportServers :        {SERVER02, SERVER01}
TlsAuthLevel :                  DomainValidation
TlsCertificateName :            <I>CN=GlobalSign Organization Validation CA - SHA256 - G2, O=GlobalSign 
                                nv-sa, C=BE;<S>CN=*.domain.uk, O=Acme Limited, L=London, S=London, C=GB
TlsDomain :                     mail.protection.outlook.com
UseExternalDNSServersEnabled :  False

The above PowerShell from the on-premises Exchange Management Shell shows you the hybrid send connector. As you can see this is set to route emails only for your hybrid address space (domainuk.mail.onmicrosoft.com in this example)

The other important attributes for EOP mail flow here are AddressSpaces, CloudServicesMailEnabled, DNSRoutingEnabled, Fqdn, RequireTLS, SmartHosts, and TLSAuthLevel. Setting these correctly on a new send connector will allow you to route other domains to EOP and then onward to the internet.

Create a new send connector

This blog is based upon information found in https://technet.microsoft.com/en-us/library/dn751020(v=exchg.150).aspx but it differs from the scenario described there within. In this scenario, as you have already run the hybrid wizard, the connector to the cloud from on-premises and from the cloud to your servers already exists. Therefore all we need to do is create an additional send connector on-premises to route all the other domains to EOP and the internet.

New-SendConnector -Name <DescriptiveName> -AddressSpaces testdomain1.com,testdomain2.com -CloudServicesMailEnabled $true -Fqdn <CertificateHostNameValue> -RequireTLS $true -DNSRoutingEnabled $false -SmartHosts <YourDomain_MX_Value> -TlsAuthLevel  CertificateValidation -Usage Internet

In the above, the connector is originally created being able to route for two test domains (written as testdomainx.com above, comma separated in the list with no spaces). This ensures that you do not break your existing mail flow but allows you to test that the connector works and then later change the connector to support * address space. The “YourDomain_MX_Prefix” is the same value as you would use in your MX to route emails to Exchange Online (tenant-prefix-com.mail.protection.outlook.com for example).

Testing the connector

In the above new send connector, testdomain1.com is a domain hosted in a different Office 365 tenant. Testdomain2.com is a domain who’s email is not hosted in Office 365 at all. You need both test scenarios, as routing to domains inside Office 365 is more likely to work if the connector is not configured properly.

So from a mailbox on-premises, send an email to a recipient at both testdomain1.com and testdomain2.com. Do not set the connector up to use gmail or Outlook.com, as that will impact other senders within your organization. Use domains that no one else is likely to want to email.

Ensure that you do not get any NDR’s and check the recipient mailboxes to ensure delivery. Note that you are possibly likely to need to update your SPF record for the sending domain to additionally include the following:

  • include:spf.protection.outlook.com
  • ipv4:w.x.y.z (where w.x.y.z is the external IP address(es) of your on-premises Exchange transport servers)

Updating the connector

Once your mail flow tests work, and you can check the route by pasting the received message headers into http://exrca.com you should see that email routes into your Office 365 tenant, then leave EOP (the word “outbound” will be in one of the FQDNs – this server is on the external edge of EOP), then routed inbound to your email provider (or back into your recipient tenant).

Once mail flow works, you can either add more recipient domains to increase the scope of the test – for example add a domain that you email occasionally, such as the partner helping you with this work and a few other domains. Once all your testing is ready change this connector to have * as the address space and not list specific domains.

As your other connector for * is still up and running you will find that 50% of your email will use the new connector and 50% the old. Then you can disable the old connector to go 100% email outbound through EOP (you need an EOP licence per sender to do this, or if you have an Exchange Online licence for each user you are already covered).

Finally when you have been routing on-premises email through EOP for a few weeks with the old connector disabled, you can delete the old connector and tidy up the configuration rather than leaving disabled connectors around.

Duplicate Exchange Online and Exchange Server Mailboxes

Posted on 4 CommentsPosted in duplicate, EOP, exchange, exchange online, Exchange Online Protection, Exchange Server, mailbox, MX, Office 365

With a hybrid Exchange Online deployment, where you have Exchange Server on-premises and Exchange Online configured in the cloud, and utilising AADConnect to synchronize the directory, you should never find that a synced user object is configured as both a mailbox in the cloud and a mailbox on-premises.

When Active Directory is synced to Azure Active Directory, the ExchangeGUID attribute for the on-premises user is synced to the cloud (assuming that you have not do a limited attribute sync and not synced the Exchange attributes – as that is required for Exchange Online hybrid). The Exchange Online directory takes a sync of information relating to Exchange from Azure Active Directory (Azure AD), which is known as forward sync. This ensures that the ExchangeGUID attribute from the on-premises mailbox is synced into your Exchange Online directory.

When a user is given an Exchange Online licence, it becomes the job of Exchange Online to provision a mailbox for this user. When Exchange Online needs to provision a new mailbox, it will not do so where the ExchangeGUID attribute already exists. The existence of this attribute tells the provisioning process that the mailbox already exists on-premises and will be migrated here later and so not to create a conflicting mailbox. A cloud user who does not have an ExchangeGUID attribute synced from on-premises will get a mailbox created by the Exchange Online provisioning process upon a licence being assigned, and on-premises users that do not have a mailbox on-premises (who also have no ExchangeGUID attribute) will also find that granting them an Exchange Online licence will trigger the creation of a mailbox for them.

This is all well and good, and the above is what happens in most cases. But there is an edge case where an on-premises user with a mailbox (and therefore has the ExchangeGUID attribute populated) will also get a mailbox in Exchange Online. This happens where the organization manually created cloud mailboxes before enabling AADConnect to sync the directories, and these cloud users match the on-premises user by UserPrincipalName and they are given an Exchange Online licence.

In this above case, because they are cloud users with an Exchange Online licence they get a mailbox. Deleting the cloud user and then enabling sync will cause the original mailbox to be restored to the user account as the UserPrincipalName matches.

For example, the below shows a user being created in the cloud called “twomailboxes@domain.com”:


The user is granted a full Office 365 E3 licence, so this means the user has an Exchange Online mailbox. There is no AADConnect sync in place, but the UPN matches a user on-premises who has a mailbox.

In Exchange Online PowerShell, once the mailbox is provisioned we can see the following:


PS> get-mailbox twomailboxes | fl name,userprincipalname,exchangeguid

Name              : twomailboxes
UserPrincipalName : twomailboxes@domain.com
ExchangeGuid      : d893372b-bfe0-4833-9905-eb497bb81de4

Repeating the same on-premises will show a separate user (remember, no AD sync in place at this time) with the same UPN and a different ExchangeGUID.


[PS] >get-mailbox twomailboxes | fl name,userprincipalname,exchangeguid

Name              : Two Mailboxes
UserPrincipalName : twomailboxes@cwh.org.uk
ExchangeGuid      : 625d70aa-82ed-47a2-afa2-d3c091d149aa

Note that the on-premises object ExchangeGUID is not the same as the cloud ExchangeGUID. This is because there are two seperate mailboxes.

Get-User in the cloud will also report something useful. It will show the “PreviousRecipientTypeDetails” value, which is not modifiable by the administrator, in this case shows there was not a previous mailbox for the user but this can show that a previous mailbox did exist. For completion we also show the licence state:


PS > get-user twomailboxes | fl name,recipienttype,previousrecipienttypedetails,*sku*

Name                         : twomailboxes
RecipientType                : UserMailbox
PreviousRecipientTypeDetails : None
SKUAssigned                  : True

Now in preparation for the sync of the Active Directory to Azure Active Directory, the user accounts in the cloud are either left in place (and so sync will do a soft-match for those users) or they are deleted and the on-premises user account syncs to the cloud. In the first case, the clash on the sync will result in the cloud mailbox being merged into the settings from the on-premises mailbox. In the second case, there is no user account to merge into, but there is a mailbox to restore against this user. And even though the newly synced user has an ExchangeGUID attribute on-premises that is synced to the cloud, and they have a valid licence, Exchange Online reattaches the old mailbox associated with a different GUID.

The impact of this is minor to massive. In the scenario where MX points to on-premises and you have not yet moved any mailboxes to the cloud, this cloud mailbox will only get email from other cloud mailboxes in your tenant (there are none in this scenario) or internal alerts in Office 365 (and these are reducing over time, as they start to follow correct routing). It can be a major issue though if you use MX to Exchange Online Protection. As there is now a mailbox in the cloud for a user on-premises, inbound internet sourced email for your on-premises user will get delivered to the cloud mailbox and not appear on-premises. Where the invalid mailbox has no email, recovery is not required. Finally, where there is a duplicate mailbox, move requests for those users for onboarding to Exchange Online will fail:


This reads “a subscription for the migration user <email> couldn’t be loaded”. This occurs where the user was not licenced and so there was not a duplicate mailbox in the cloud, but the user was later licenced before the migration completed.

Where the invalid duplicate mailbox exists in the cloud and is getting valid emails delivered to it, the recovery work described below additionally will involve exporting email from this invalid mailbox and then removing the mailbox as part of the fix. Extraction of email from the duplicate mailbox needs to happen before the licence is removed.

To remove the cloud mailbox and to stop it being recreated, you need to ensure that the synced user does not have an Exchange Online licence. You can grant them other licences in Office 365, but not Exchange Online. I have noticed that if you do licencing via Azure AD group based licencing rules then this will also fail (these are still in preview at time of writing) and that you need to ensure that the user is assigned the licence directly in the Office 365 portal and that they do not get the Exchange Online licence. After licence reconciliation in the cloud occurs (a few minutes typically) the duplicate mailbox is removed (though I have seen this take a few hours). The Get-User cmdlet above will show the RecipientType being a MailUser and not Mailbox.

You are now in a position where your duplicate cloud mailbox is gone (which is why if that mailbox had been a target to valid emails before now, you would need to have extracted the data via discovery and search processes first).

Running the above Get-User and Get-Mailbox (and now Get-MailUser) cmdlets in the cloud will show you that the ExchangeGUID on the cloud object now matches the on-premises object and the duplication is gone. You can now migrate that mailbox to the cloud successfully.

We can take a look at what we see in remote PowerShell here:

Recall from above that there were two different ExchangeGUIDs, one in the cloud and one on-premises. These in my example where:

Cloud duplicate ExchangeGuid      : d893372b-bfe0-4833-9905-eb497bb81de4

On-premises mailbox ExchangeGuid  : 625d70aa-82ed-47a2-afa2-d3c091d149aa

Get-User before licences removed in the cloud, showing a mailbox and that it was previously a mailbox as well:


PS > get-user twomailboxes | fl name,recipienttype,previousrecipienttypedetails,*sku*

Name                         : Two Mailboxes
RecipientType                : UserMailbox
PreviousRecipientTypeDetails : UserMailbox
SKUAssigned                  : True

Get-Mailbox in the cloud showing the GUID was different from on-premises:


PS > get-mailbox twomailboxes | fl name,userprincipalname,exchangeguid

Name              : Two Mailboxes
UserPrincipalName :

ExchangeGuid      : d893372b-bfe0-4833-9905-eb497bb81de4

Once the licence is removed in Office 365 for Exchange Online and licence reconciliation completes (SKUAssigned is False) you will see that Get-User shows it is not a mailbox anymore:


PS > get-user twomailboxes | fl name,recipienttype,previousrecipienttypedetails,*sku*

Name                         : Two Mailboxes
RecipientType                : MailUser
PreviousRecipientTypeDetails : UserMailbox
SKUAssigned                  : False

And finally Get-MailUser (not Get-Mailbox now) shows the ExchangeGUID matches the on-premises, synced, ExchangeGUID value:


PS > get-mailuser twomailboxes | fl name,userprincipalname,exchangeguid

Name              : Two Mailboxes
UserPrincipalName : twomailboxes@domain.com
ExchangeGuid      : 625d70aa-82ed-47a2-afa2-d3c091d149aa

Note that giving these users back their Exchange Online licence will revert all of the above and restore their old mailbox. As these users cannot have an Exchange Online licence assigned in the cloud, for risk of their old mailbox returning you need to ensure that within 30 days of their on-premises mailbox being migrated to the cloud you do give then an Exchange Online mailbox. Giving them a licence after migration of their on-premises mailbox to the cloud will ensure their single, migrated, mailbox remains in Exchange Online. But giving their user a licence before migration will restore their old cloud mailbox.

For users that never had a matching UPN in the cloud and a cloud mailbox, you can licence them before you migrate their mailbox as they will work correctly within the provisioning system in Exchange Online.

DMARC Quarantine Issues

Posted on Leave a commentPosted in dkim, dmarc, EOP, exchange, exchange online, Exchange Online Protection, Exchange Server, spf, spoof

I saw the following error with a client the other day when sending emails from the client to any of the Virgin Media owned consumer ISP email addresses (virginmedia.com, ntlworld.com, blueyonder.com etc.)

mx3.mnd.ukmail.iss.as9143.net gave this error:
vLkg1v00o2hp5bc01Lkg9w DMARC validation failed with result 3.00:quarantine

In the above, the server name (…as9143.net) might change as will the value before the error, but either DMARC validation failed with result 3.00:quarantine or 4.00:reject is the end of the error message.

We resolved this error by shorting the DMARC record of the sending organization. Before we made the change we had a DMARC record of 204 characters. We cannot find a reference online to the maximum length of a DMARC record, though we could successfully add a record of this length to Route 53 DNS provided by AWS, though a record of 277 characters was not allowed in AWS. Other references online to domain character length seem to imply that 255 characters is the max, but not specifically for DMARC.

So, shortening the DMARC record to remove two of the three email addresses in each of the RUA and RUF values was the fix that we needed. This change was done for two reasons, first the above error occurred only with emails to Virgin Media and sometimes an NDR would be received and other times the NDR would fail, but the original email never made it through and secondly the two removed email addresses where not actively being checked for DMARC status messages anyway and so there is no harm in the removal of them from the DMARC record anyway!

The original DMARC record we had this issue with looked like this (xxx.xxxxx representing the client domain):

v=DMARC1; p=quarantine; fo=1;rua=mailto:admin@xxx.xxxxx,mailto:dmarc-rua@dmarc.service.gov.uk,mailto:dmarc@xxx.xxxxx;ruf=mailto:admin@xxx.xxxxx,mailto:dmarc-ruf@dmarc.service.gov.uk,mailto:dmarc@xxx.xxxxx;

Then we changed the record to the following to resolve it:

v=DMARC1; p=quarantine; fo=1;rua=mailto:dmarc-rua@dmarc.service.gov.uk;ruf=mailto:dmarc-ruf@dmarc.service.gov.uk;

Reducing the length of the record resulted in DMARC analytics and forensic email not going to mailboxes at the client (one of whom those mailboxes did not exist anyway) and only going to the UK government DMARC policy checking service, but most importantly for a client that has a requirement to respond to citizen’s emails (and whom could easily be using Virgin Media email addresses) we resolved the issue.

XOORG, Edge and Exchange 2010 Hybrid

Posted on 2 CommentsPosted in 2010, Edge, EOP, exchange, exchange online, Exchange Online Protection, Exchange Server, Office 365

So you have found yourself in the position of moving to Exchange Online from a legacy version of Exchange Server, namely Exchange 2010. You are planning to move everyone, or mostly everyone to Exchange Online and directory synchronization plays a major part (can it play a minor part?) in your plans. So you have made the option to go hybrid mode when you discover that there are manual steps to making Exchange 2010 mail flow to Exchange Online work if you have Exchange Edge Servers in use.

So, what do you do. You look online and find a number of references to setting up XOORG, but nothing about what that is and nothing about what you really need to do. And this you found this article!

So, how do you configure Exchange Server 2010 with Edge Servers, so that you can have hybrid mode to Exchange Online.

Why You Need These Steps

So you ran the hybrid wizard, and it completed (eventually if you have a large number of users) and you start your testing only to find that emails never arrive in Office 365 whilst your MX record is still pointing on-premises. After a while you start to get NDR’s for your test emails saying “#554 5.4.6 Hop count exceeded – possible mail loop” and when you look at the diagnostic information for administrators at the bottom of the NDR you see that your email goes between the hub transport servers and the edge servers and back to the hub transport servers etc. and about three or so hours after sending it, with the various timeouts involved, the email NDR arrives and the message is not sent.

The problem is that the Edge Server sees the recipient as internal, and not in the cloud, as the email has been forwarded to the user@tenant.mail.onmicrosoft.com, and Exchange 2010 is authoritative for this namespace. You are missing a configuration that tells the Edge that some emails with certain properties are not internal, but really external and others (those coming back from the cloud) are the only ones to send internal to the on-premises servers.

So what do you do?


Before you run the hybrid wizard you need to do the following. If you have already run the wizard that is fine, you will do these steps and run it again.

  1. Install a digital certificate on all your Edge Servers that is issued by a trusted third party (i.e. GoDaddy, Digicert and others). The private key for this certificate needs to be on each server as well, but you do not need to allow the key to be exported again.
  2. Enable the certificate for SMTP, but ensure you do not set it as the default certificate. You do this by using Exchange Management Shell to Get-ExchangeCertificate to key the key’s thumbprint value and then running Enable-ExchangeCertificate –Thumbrint <thumbprintvalue> –Services SMTP. At this point you are prompted if you want to set this certificate as the default certificate. The answer is always No!
  3. If you answer yes, then run the Enable-ExchangeCertificate cmdlet again, but this time for the certificate thumbprint that was the default and set the default back again. If you change the default you will break EdgeSync and internal mail flow for everyone. And you must use the self-signed certificate for EdgeSync and this third party issued certificate for cloud mail flow, as you cannot use the same certificate for both internal and external traffic.
  4. The certificate needs to be the same across all your Edge Servers.
  5. If you are doing multi-forest hybrid, then the certificate is only the same across all the Edge Servers in one Exchange Organization. The next organization in your multi-forest hybrid needs to use a different certificate for all its Edge Servers.
  6. Then take this same certificate and install it on a single Hub Transport server on-premises. The hybrid wizard cannot see what certificates you have on the Edge Servers, so you need to help the wizard along a bit. Again, this certificate needs enabling for SMTP, but not setting as the default certificate.

Running The Hybrid Wizard

Now you can run the hybrid wizard. The important answers you need to include here are that the hub transport server that you pick must be the one that you placed the certificate on, as you cannot pick the Edge Servers that you will use for mail flow in the wizard. But you will need to enter the IP addresses that your Edge Servers are published on the internet as, and you will need to enter the FQDN of the Edge Servers as well.

Complete the wizard and then time for some manual changes.

Manual Changes

The hybrid wizard will have made a send connector on-premises called “Outbound to Office 365”. You need to change this connector to use the Edge Servers as the source servers. Note that if you run the hybrid wizard again, you might need to reset this value back to the Edge Servers. So once all these required changes are made, remember that running the wizard again could constitute an unexpected change and so should be run with care or out of hours.

Use Set-SendConnector “Outbound to Office 365” -SourceTransportServers <EDGE1>,<EDGE2> and this will cause the send connector settings to replicate to the Edge Server.

Next get a copy of the FQDN value from the receive connector that the hybrid wizard created on the hub transport server. This receive connector will be called “Inbound from Office 365” and will be tied to the public IP ranged of Exchange Online Protection. As your Edge Servers receive the inbound emails from EOP, this receive connector will serve no purposes apart from the fact that its settings are the template for your receive connector on the Edge Servers that the wizard cannot modify. The same receive connector will also have a setting called TlsDomainCapabilities and the value of this setting will be mail.protection.outlook.com:AcceptOorgProtocol. AcceptOorgProtocol is the XOORG value that you see referenced on the internet, but it is really called AcceptOorgProtocol and this is the value that allows the Edge Server to distinguish between inbound and outbound mail for your Office 365 tenant.

So on each Edge Server run the following cmdlet in Exchange Management Shell to modify the default receive connector: Set-ReceiveConnector *def* -TlsDomainCapabilities mail.protection.outlook.com:AcceptOorgProtocol -Fqdn <fqdnFromTheInboundReceiveConnectorOnTheHubTransportServer>.

This needs repeating on each Edge Server. The FQDN value ensures that the correct certificate is selected and the TlsDomainCapabilities setting ensures you do not loop email to Office 365 back on-premises again. Other emails using the Default Receive Connector are not affected by this change, apart from now being able to offer the public certificate as well to their inbound partners.

You can now continue with your testing knowing that mail flow is working, so now onto AutoDiscover, clients, free/busy, public folders etc. etc. etc.

OWA and Conditional Access: Inconsistent Error Reports

Posted on 1 CommentPosted in AzureAD, conditional access, EM+S, enterprise mobility + security, exchange, exchange online, Exchange Online Protection, IAmMEC, Outlook

Here is a good error message. Its good, because I could not find any references to it on Google and the fault was nothing to do with the error message:


The error says “something went wrong” and “Ref A: a long string of Hex Ref B: AMSEDGE0319 Ref C: Date Time”. The server name in Ref B will change as well. It also says “more details” and if you click that there are no more details, but that text changes to “fewer details”. As far as I have seen, this only appears on Outlook Web Access (OWA).

The error appears under these conditions:

  1. You are enabled for Enterprise Mobility + Security licences in Azure AD
  2. Conditional Access rules are enabled
  3. The device you are on, or the location you are at etc (see the specifics of the conditional access rule) mean that you are outside the conditions allowed to access Outlook Web Access
  4. You browsed directly to https://outlook.office.com or https://outlook.office365.com

What you see in the error message is OWA’s way of telling you that you cannot get to that site from where you are. That you have failed the conditional access tests.

On the other hand, if you visit the Office 365 portal or MyApps (https://portal.office.com or https://myapps.microsoft.com) and click the Mail icon in your Office 365 menu or on the portal homepage then you get a page that says (in the language of your browser):

image or in Welsh, image

This says “you can’t get there from here” and the reasons why you have failed conditional access.

If you were on a device or location that allowed you to connect (such as a device managed by Intune and compliant with Intune rules) then going to OWA directly will work, as will going via the menu.

So how can you avoid this odd error message for your users. For this, you need to replace outlook.office.com with your own custom URL. For OWA you can create a DNS CNAME in your domain for (lets say) webmail that points to outlook.office365.com (for this it will not work if you point the CNAME to outlook.office.com). Your users can now go to webmail.yourdomain.com. This will redirect the user via Azure AD for login and token generation, and as you are redirected via Azure AD you will always see the proper, language relevant, conditional access page.

Administrators, AADConnect and AdminSDHolder Issues (or why are some accounts having permission-issue)

Posted on 2 CommentsPosted in AADConnect, AADSync, active directory, AdminSDHolder, dirsync, exchange, exchange online, hybrid, Office 365

[Scripts updated 5th October 2017 to support updates for Exchange Hybrid Writeback. If you ran earlier versions of these scripts you will need to run them again]

AdminSDHolder is something I come across a lot, but find a lot of admins are unaware of it. In brief it is any user that is a member of a protected group (i.e. Domain Admins) will find that their AD permission inheritance and access control lists on their AD object will be reset every hour. Michael B. Smith did a nice write-up on this subject here.

AdminSDHolder is an AD object that determines what the permissions for all protected group members need to be. Why this matters with AADConnect and your sync to Azure Active Directory (i.e. the directory used by Office 365) is that any object that the AADConnect service cannot read cannot be synced, and any object that the AADConnect service cannot write to can be targeted by writeback permissions. This blog post was last updated 18th June 2017 in advance of the release of AADConnect version 1.1.553.0.

For the read permissions this is less of an issue, as the default read permissions by every object is part of a standard Active Directory deployment and so you will find that AdminSDHolder contains this permission and therefore protected objects can be read by AADConnect. This happens in reality becase Authenticated Users have read permissions to lots of attributes on the AdminSDHolder object under the hidden System containing in the domain. Unless your AD permissions are very locked down or AdminSDHolder permissions have been changed to remove Authenticated Users you should have no issue in syncing admin accounts, who of course might have dependencies on mailboxes and SharePoint sites etc. and so need to be synced to the cloud.

Writeback though is a different ball game. Unless you have done AADConnect with Express settings you will find that protected accounts fail during the last stage of AADConnect sync process. You often see errors in the Export profile for your Active Directory that list your admin accounts. Ofter the easiest way to fix this is to enable the Inheritance permission check box on the user account and sync again. The changes are now successfully written but within the hour this inheritance checkbox will be removed and the default permissions as set on AdminSDHolder reapplied to these user accounts. Later changes that need written back from the cloud will result in a failure to writeback again, and again permission issues will be to blame.

To fix this we just need to ensure that the AdminSDHolder object has the correct permissions needed. This is nothing more than doing what the AADConnect Express wizard will do for you anyway, but if you don’t do the Express wizard I don’t think I have seen what you should do documented anywhere – so this is the first (maybe).

Often if you don’t run Express settings you are interested in the principal of least privilege and so the rest of this blog post will outline what you will see in your Active Directory and what to do to ensure protected accounts will always sync and writeback in the Azure Active Directory sync engine. I covered the permissions to enable various types of writeback permissions in a different blog post, but the scripts in this post never added the correct write permissions to AdminSDHolder, so this post will cover what to do for your protected accounts.

First, take a look at any protected account (i.e. one that is a member of Domain Admins):

You will see in the Advanced permissions dialog that their is an “Enable Inheritance” button (or a check box is unchecked in older versions of Active Directory. You will also notice that all the permissions under the “Inherited From” column read “None” – that is there are no permissions inherited. You will also see, as shown in the above dialog, that if Express settings have been run for your AADConnect sync service that a access control entry for the AADConnect service account will be listed – here this is MSOL_924f68d9ff1f (yours will be different if it exists) and has read/write for everything. This is not least privilege! If you have run the sync engine previously on different servers and later removed them (as the sync engine can only run on one server to one AAD tenant, excluding staging servers) then you might see more than one MSOL account. The description field of the account will show what server it was created on for your information.

If you compare your above admin account to a non-protected account you will see inheritance can be disabled and that the Inherited From column lists the source of the permission inheritance.

Compare the access control entries (ACE) to the list of ACE’s on the AdminSDHolder object. AdminSDHolder can be found at CN=AdminSDHolder,CN=System,DC=domain,DC=local. You should find that the protected accounts match those of the AdminSDHolder, or at least will within the hour as someone could have just changed something.

Add a permission ACE to AdminSDHolder and it will appear on each protected account within an hour, remove an ACE and it will go within the hour as well. So you could for example remove the MSOL_ account(s) from older ADSync deployments and tidy up your permissions as well.

This is what my Advanced permissions for AdminSDHolder looks like on my domain


If I add the relevant ACE’s here for the writeback permissions then within the hour, and then for syncs that happen after that time, the errors for writeback in the sync management console will go away. Note though that AdminSDHolder is per domain, so if you are syncing more than one domain you need to set these permissions on each domain.

To script these permissions, run the following in PowerShell to update AD permissions regarding to the different hybrid writebacks scenarios that you are interested in implementing.

Finding All Your AdminSDHolder Affected Users

The following PowerShell will let you know all the users in your domain who have an AdminCount set to 1 (>0 in reality), which means they are impacted by AdminSDHolder restrictions. The changes below directly on the AdminSDHolder will impact these users as their permissions will get updated to allow writeback from Azure AD.

get-aduser -Filter {admincount -gt 0} -Properties adminCount -ResultSetSize $null | FT DistinguishedName,Enabled,SamAccountName

SourceAnchor Writeback

This setting is needed for all installations since version 1.1.553.0.

$accountName = "domain\aad_account" #[this is the account that will be used by Azure AD Connect Sync to manage objects in the directory, this is an account usually in the form of AAD_number or MSOL_number].
$AdminSDHolder = "CN=AdminSDHolder,CN=System,DC=contoso,DC=com"

$cmd = "dsacls.exe '$AdminSDHolder' /G '`"$accountName`":WP;ms-ds-consistencyGuid'"
Invoke-Expression $cmd | Out-Null

Password Writeback

The following PowerShell will modify the permissions on the AdminSDHolder object so that protected accounts can have Self Service Password Reset (SSPR) function against the accounts. Note you need to change the DC values in the script for it to function against your domain(s).

Note that if you implement this, I recommend that you use version 1.1.553 or later, as that version restricts rogue Azure AD admins from resetting other Active Directory admins passwords and then taking ownership of the Active Directory account. Often Azure AD admins have admin rights in AD, and so this was always possible independent of AADConnect, but versions of AADConnect prior to 1.1.553 would allow an Azure AD admin to reset a restricted AD account that they did not own.

To determine the account name that permissions must be granted to, open the Synchronization Service Manager on the sync server, click Connectors and double click the connector to the domain you are updating. Under the Connect to Active Directory Forest item you will see the Forest Name and User Name. The User Name is the name of the account you need in the script. An example is shown below:


$accountName = "domain\aad_account" #[this is the account that will be used by Azure AD Connect Sync to manage objects in the directory, this is an account usually in the form of AAD_number or MSOL_number].
$AdminSDHolder = "CN=AdminSDHolder,CN=System,DC=contoso,DC=com"

$cmd = "dsacls.exe '$AdminSDHolder' /G '`"$accountName`":CA;`"Reset Password`"'"
Invoke-Expression $cmd | Out-Null
$cmd = "dsacls.exe '$AdminSDHolder' /G '`"$accountName`":CA;`"Change Password`"'"
Invoke-Expression $cmd | Out-Null
$cmd = "dsacls.exe '$AdminSDHolder' /G '`"$accountName`":WP;lockoutTime'"
Invoke-Expression $cmd | Out-Null
$cmd = "dsacls.exe '$AdminSDHolder' /G '`"$accountName`":WP;pwdLastSet'"
Invoke-Expression $cmd | Out-Null

Exchange Hybrid Mode Writeback

The below script will set the permissions required for the service account that AADSync uses. Note that if Express mode has been used, then an account called MSOL_AD_Sync_RichCoexistence will exist that has these permissions rather than being assigned directly to the sync account. Therefore you could change the below permissions to utilise MSOL_AD_Sync_RichCoexistence rather than AAD_ or MSOL_ and achieve the same results, but knowing that future changes to the MSOL_ or AAD_ account will be saved as it was done via a group.

The final permission in the set is for msDS-ExternalDirectoryObjectID and this is part of the Exchange Server 2016 (and maybe Exchange Server 2013 later CU’s) schema updates. Newer documentation on AAD Connect synchronized attributes already has this attribute listed, for example in Azure AD Connect sync: Attributes synchronized to Azure Active Directory

$accountName = "domain\aad_account"
$AdminSDHolder = "CN=AdminSDHolder,CN=System,DC=contoso,DC=com"

$cmd = "dsacls '$AdminSDHolder' /G '`"$accountName`":WP;proxyAddresses'"
Invoke-Expression $cmd | Out-Null
$cmd = "dsacls '$AdminSDHolder' /G '`"$accountName`":WP;msExchUCVoiceMailSettings'"
Invoke-Expression $cmd | Out-Null
$cmd = "dsacls '$AdminSDHolder' /G '`"$accountName`":WP;msExchUserHoldPolicies'"
Invoke-Expression $cmd | Out-Null
$cmd = "dsacls '$AdminSDHolder' /G '`"$accountName`":WP;msExchArchiveStatus'"
Invoke-Expression $cmd | Out-Null
$cmd = "dsacls '$AdminSDHolder' /G '`"$accountName`":WP;msExchSafeSendersHash'"
Invoke-Expression $cmd | Out-Null
$cmd = "dsacls '$AdminSDHolder' /G '`"$accountName`":WP;msExchBlockedSendersHash'"
Invoke-Expression $cmd | Out-Null
$cmd = "dsacls '$AdminSDHolder' /G '`"$accountName`":WP;msExchSafeRecipientsHash'"
Invoke-Expression $cmd | Out-Null
$cmd = "dsacls '$AdminSDHolder' /G '`"$accountName`":WP;msDS-ExternalDirectoryObjectID'"
Invoke-Expression $cmd | Out-Null
$cmd = "dsacls '$AdminSDHolder' /G '`"$accountName`":WP;publicDelegates'"
Invoke-Expression $cmd | Out-Null
$cmd = "dsacls '$AdminSDHolder' /G '`"$accountName`":WP;msExchDelegateLinkList'"
Invoke-Expression $cmd | Out-Null

Once these two scripts are run against AdminSDHolder object and you wait an hour, the permissions will be applied to your protected accounts, then within 30 minutes (based on the default sync time) any admin account that is failing to get cloud settings written back to Active Directory due to permission-issue errors will automatically get resolved.

Exchange Edge Server and Common Attachment Blocking In Exchange Online Protection

Posted on Leave a commentPosted in 2007, 2010, 2013, 2016, Edge, EOP, exchange, exchange online, Exchange Online Protection, FOPE, IAmMEC, Office 365

Both Exchange Server Edge role and Exchange Online Protection have an attachment filtering policy. The default in Edge Server is quite long, and the default in EOP is quite short. There is also a few values that are common to both.

So, how do you merge the lists so that your Edge Server attachment filtering policy is copied to Exchange Online in advance of changing your MX record to EOP?

You run

Set-MalwareFilterPolicy Default -FileTypes ade,adp,cpl,app,bas,asx,bat,chm,cmd,com,crt,csh,exe,fxp,hlp,hta,inf,ins,isp,js,jse,ksh,lnk,mda,mdb,mde,mdt,mdw,mdz,msc,msi,msp,mst,ops,pcd,pif,prf,prg,ps1,ps11,ps11xml,ps1xml,ps2,ps2xml,psc1,psc2,reg,scf,scr,sct,shb,shs,url,vb,vbe,vbs,wsc,wsf,wsh,xnk,ace,ani,docm,jar

This takes both the Edge Server default list and the EOP default list, minus the duplicate values and adds them to EOP. If you have a different custom list then use the following PowerShell to get your two lists and then use the above (with “Default” being the name of the policy) PowerShell to update the list in the cloud

Edge Server: Get-AttachmentFilterEntry

EOP: $variable = Get-MalwareFilterPolicy Default

Exchange Online Archive–Counting Archives

Posted on Leave a commentPosted in archive, exchange, exchange online, Exchange Server, EXO, IAmMEC, Office 365

If you are using Exchange Online Archive and what to get a count of the number of users with an archive, or a list of the users with an archive, then the following PowerShell scripts will give you this info:

List all users with an Exchange Online Archive:

Get-MailUser -ResultSize Unlimited | where {$_.ArchiveName -ilike “In-Place Archive*”}

Count all users with an Exchange Online Archive:

(Get-MailUser -ResultSize Unlimited | where {$_.ArchiveName -ilike “In-Place Archive*”}).Count

Both of these PowerShell cmdlets need to be run in Exchange Online via Remote PowerShell.