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… Continue reading Gmail showing “via” in Microsoft 365 Email Headers

Outbound Email Via Exchange Online Protection When Using Hybrid Exchange Online

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… Continue reading Outbound Email Via Exchange Online Protection When Using Hybrid Exchange Online

DMARC Quarantine Issues

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… Continue reading DMARC Quarantine Issues