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Blocking More Obvious Phish – Attachment Filtering
One relatively easy way to block some categories of phishing email is to block the attachment type that is sent with some of these messages. For example, I have had a few of these recently: Hovering over the attachment I see the filename, and it ends .shtml. This attachment is for server-side HTML (SSI includes […]
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Exchange Hybrid Wizard – New Tenants and Missing Errors
A short blog post on this issue – you see in the Microsoft Exchange Server Hybrid Configuration Wizard logs the following error “Connecting to remote server failed with the following error message: Connecting to remote server outlook.office365.com failed with the following error message : For more information, see the about_Remote_Troubleshooting Help topic.”. The error does […]
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Managing Hybrid Exchange Online Without Installing an Exchange Server
In April 2022 Microsoft finally released the ability to manage Active Directory synced attributes (Hybrid Identity) to Azure Active Directory for Exchange without a full Exchange Server installation. You have instead an install of the Exchange Management Tools. You need to be Exchange Server 2019 CU12 to do this, and you either uninstall your existing […]
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Improving Exchange Online Email Deliverability Through Third Party Filtering Services – Trusted ARC Sealer
When you receive emails into Exchange Online and you filter the external messages before arrival with a third party filter such as Mimecast, Proofpoint or others, then you can have DMARC failures that result in messages being junked or quarantined. This is a new feature to Exchange Online to allow you to trust the DMARC […]
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Gmail showing “via” in Microsoft 365 Email Headers
I came across this issue the other day. In the headers of an email received from Microsoft 365 / Exchange Online into Gmail (and not other recipients) the message header reads “name@domain via otherdomain.onmicrosoft.com”, for example: In this case the via header for onmicrosoft.com was an old organization name and as tenant rename does not […]
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Finding Existing Plus Addresses
Exchange Online will automatically enable “Plus Addressing” for all tenants from Jan 2022. This change may cause issues if you have existing mailboxes where the SMTP address contains a + sign. That is, directors+managers@contoso.com would be considered a broken email address from Jan 2022 in Exchange Online. So you need to check you have no […]
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Outlook AutoDetect And Broken AutoDiscover
Those in the Exchange Server space for a number of years know all about AutoDiscover and the many ways it can be configured and misconfigured – if even configured at all. Often misconfiguration is to do with certificates or it is not configured at all because it involves certificates and I thought I was aware […]
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550 5.1.8 Access denied, bad outbound sender AS(42003)
“Your message couldn’t be delivered because you weren’t recognized as a valid sender. The most common reason for this is that your email address is suspected of sending spam and it’s no longer allowed to send email. Contact your email admin for assistance.” This is an error you get when your anti-spam “outbound” policy restricts […]
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[New] External Email Notification in Exchange Online
This is a new feature released in March 2021 that adds support in Outlook (Mac, OWA, Mobile) for the display of the external status of the sender – note at the time of writing it does not add this feature to Outlook for the PC. This should be used to replace the way this has […]
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Azure AD Consent For Zoom App Not Applying
This is a issue where you enabled Admin Approved Consent in Azure AD (as you should) and you require apps that have high data access rights to be approved. The Zoom add-in/desktop app falls into this category as it requires write access to your calendar and your contacts in Exchange Online. But if you set […]
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iOS and Outlook Mobile and Duplicate Contacts
Of the back of a few conversations recently on having duplicate contacts in the iOS platform because of syncing via multiple different routes or devices I decided to try to reproduce the issues and see what I could work out. I looked on my test iPhone to see if I could see any duplicates and […]
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Why Do Comments In Microsoft 365 Planner Disappear?
So first you need an Exchange Online mailbox for comments to work. Comments to the tasks of Plans are stored in the Microsoft 365 Group mailbox, and you need an Exchange Online mailbox to access the M365 Group mailbox. Behind the scenes, or actually not that behind the scenes, the process for comments is as […]
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Exchange Online Warning On Receipt Of New Email Sender
Released recently to no fanfare at all, Microsoft now has a SafetyTip that appears if you receive email from a first time recipient. Most often phish emails will come from an address you have never received email from before, and sometimes this email will try to impersonate people you communicate with or are internal to […]
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Microsoft 365 From A Raspberry Pi 400 Personal Computer
So my new computer arrived today, its a keyboard and a few cables, and as my first computer was a ZX Spectrum when I was 14, this brings back a few memories. But, is it usable today with services such as Microsoft 365? Lets see… First, the actual computer is in the keyboard, but its […]
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Enabling Better Mail Flow Security for Exchange Online
At Microsoft Ignite 2020, Microsoft announced support for MTA-STS, or Mail Transfer Agent Strict Transport Security. This is covered in RFC 8461 and it includes making TLS for mail flow to your domains mandatory whereas it is currently down to the decision of the sender. You can publish your SMTP endpoint and offer the STARTTLS […]
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Reporting on MTA-STS Failures
This article is a follow up to the Enabling Better Mail Flow Security for Exchange Online which discusses setting up MTA-STS and in this article we cover the reporting for MTA-STS. To get daily reports from each sending infrastructure to receive reports on MTA-STS you just create a DNS record in the following format: It […]