Thank you very much for your collaboration. we are still investigating the issue.
Apart from that I re-checked your logs and found this:
Authentication failed; nested exception is javax.mail.AuthenticationFailedException: No authentication mechanisms supported by both server and client
That is an outgoing email, as you said the outgoing was working, is that an older error?
Also, the configuration you provided has:
From the Alfresco docs, it seems that parameter should be a host, is
Exchange translated to an IP in your machine?
Specifies the host name of the SMTP host, that is, the host name or IP address of the server to which email should be sent.
Thanks for your patient we will continue investigating the issue.