Recipients using Outlook and Gpg4win can no longer automatically decrypt Mails sent from MacOS Mail after migrating to O365

Until recently, we had our mail account hosted at some cloud provider ( provided IMAP, SMTP). This allowed us e.g. to send encrypted emails to recipients and them to automatically decrypt our mails e.g. in Outlook on Windows using the gpg4win plugin. On our side, we are using MacOS with the standard mail client and the GPG suide by

Now we have changed our mail provider to Microsoft 365 - keeping the same email addresses and gpg keys. Sending and receiving emails still works perfectly well.

However, several recipients of emails report that they no longer are able to automatically decrypt emails sent by us. Within Outlook they are just shown the encrypted file “encrypted.asc” - although they were previously able to automatically decrypt and read the mails using gpg4win inside Outlook. Note that the gpg signatures and mail addresses used did not change.

In the enclosed image you can see what it looks like in Outlook when they receive our encrypted mails

Note that the recipients are able to decrypt the message outside of Outlook - after having stored the file manually and using Kleopatra.

Does anybody have a clue what could be the reason for this - and most importantly: how to fix this?

Note that I already created a separate ticket in the gpgmail support forum in order to find out whether this might be a problem of gpgmail.

Some technical details:

  • we use current MacOS 13.5.1 and the current version of gpgmail (version 7.2)
  • our recipients use Outlook and gpg4win in the current version 4.2.0
  • we use O365 with Exchange

Thanks a lot for any help.

Regards, Max.

This sounds a lot like an issue we were reported recently also together with Apple Mail ⚓ T6686 GPG4win exchange issue decrypt message from Macos GPGtools the good news is that we were able to fix / workaround the issue, but so far there is no release with that fix available :confused: So you will have to wait for the next Gpg4win release to get the fix.

Hi @aheinecke , thanks a lot for your information. (And sorry, although I did some investigation before, I did not find this ticket that seems to refer to the same problem …)
But this gives me hope …!!!
Are there already any rough time estimates when to expect the new Gpg4win release?

Regards, Max.

Oh, forgot to mention it here, there is a beta version with the fix: