Mathieu R.: > As it seem to be a good advice, I did change my dns entries for > mx to mail.effraie.org, wich is covered by the (new) cacert > certificat of the mail server. > > I still have the same error in logs
It does not matter what the server certificate says, because it is never sent. The evidence shows that the client hangs up before the TLS handshake. Wietse