365 Encrypted Email Decryption Issues

jstein — Thu, 22 Aug 2024 21:45:37 GMT

In June, for some reason users receiving encrypted emails in Outlook could no longer access them. If they go to the Outlook web client it works fine and if we exclude their IP from encryption, it works fine. It is definitely related to decryption. We have tried excluding every URL that we can find Microsoft is using but have had no luck. There are no errors in the decryption log. Does anyone have any recommendations on other things to check or ran across this? Supports recommendation at the moment is to just exempt all of the affected workstations from decryption which is not a long term solution.

Re: 365 Encrypted Email Decryption Issues

BPry — Fri, 23 Aug 2024 17:10:56 GMT

@jstein,

Unfortunately this really is more of a log hunt activity to find the right resource. The issue that you'll have is that the decryption likely isn't errorring, but rather cert-pinning is in use so it doesn't display properly unless the cert matches what is expected (which is what you want on encrypted email).

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365 Encrypted Email Decryption Issues

Re: 365 Encrypted Email Decryption Issues