Advisory: Sophos Endpoint - "Your connection isn't private" We're aware of a certificate issue and are actively working to resolve. Please see: KB-000045954 for the latest updates.

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Sophos UTM, DKIM and Microsoft-hosted email servers

Hi all

Has anyone managed to set up DKIM signatures that work in Exchange and other Microsoft mail sites?

I've followed the instructions in KB-000034259 and the DKIM check passes if I send to certain mail providers, e.g. Gmail,, AOL, BTInternet; however the DKIM check fails if it's sent to anything hosted by Microsoft. The error I get is 'dkim=fail (signature did not verify)'.

I've tried changing the keys, using 1024-bit and 2048-bit keys, hosting the DNS selector record on a different DNS server, and different UTMs, but all to no avail. If I send an email to two recipients - one on a Microsoft-hosted email server and the other on Gmail, for example - DKIM passes on Gmail but fails on Microsoft.

Is it only me who sees this issue?


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