It works! Thanks!
OS: Ubuntu 20.04 - Linux 5.4.0-29-generic #33-Ubuntu SMP Logwatch: logwatch/focal-updates,focal-updates,now 7.5.2-1ubuntu1.2 all Postfix: postfix/focal-updates,now 3.4.13-0ubuntu1 amd64 This is an example line from mail.log (default postfix installation) May 18 10:47:41 myserver postfix/relay/smtp[12833]: 945Z14EA: to=<someone@somewhere.com>, relay=other.server.com[192.168.0.1]:25, delay=10, delays=5.2/0.01/1.4/3.6, dsn=2.0.0, status=sent (250 2.0.0 Ok: queued as 4F43X645FA) Default service config...