Date: Tuesday, October 18, 2016 13:12:39 +0200 From: Moi <anic297@mac.com>

Thank you. It worked and I now have several log files to check.

In the meantime, I've tried once again to send a message to "mailtest" from an outside address; this time, I got an error reply:

This report relates to a message you sent with the following header fields:

Message-id: <00e201d2290f$67da8c70$378fa550$@mac.com> Date: Tue, 18 Oct 2016 09:15:21 +0200 From: Moi To: 'Mail Test' <mailtest@barbu.sytes.net> Subject: Test

Your message cannot be delivered to the following recipients:

Recipient address: mailtest@barbu.sytes.net Reason: Illegal host/domain name found <end of reply>

Yet another area with a problem; at least this is now a valid reason for it to not work. Is this a misconfiguration of my DNS server?

Assuming that "barbu.sytes.net" is the intended hostname (not something made up to obscure the real name), there is an MX-record for that that points to "mail.barbu.sytes.net", but there is no A-record for the "mail." hostname. There is an A-record for "mail.sytes.net", in case that is what you were intending, in which case you'd need to fix the MX on "barbu.sytes.net".