Hi - that did the trick. The linked gpgol.dll loads without any issues. However the decryption of e-Mails don't work. I get the
"OpenPGP Encrypted message (decryption not possible) Could not decrypt the data: Unsupported protocol" error.

Since I configured call tracing the running O365 Client dies immediately after activating the addin. Same happens now if I activate the addin.
Anyways, here is the log.