There is an issue when the name of the sender (not the E-Mail Address) contains special charcters like german umlauts - ä, ö, ü.
The mail will be successfully accepted from SMTP2Graph but not forwarded to EXO. The error.log shows: "No sender/from address defined".

Is there a way to fix this ?
As workaround i temporary removed the special charecters in the name field in the mail client options.

Thx!