🚀 go-pugleaf

You must let sendmail know in the configuration file that host.domain is
the same as host which is the same as YOU.  No havig your sendmail.cf file
in front of me I can't tell you where to fix it but it should be
somewhere near where you handle anything.yourdomain.  Stick a line in
to resolve that just hostname (if you want) or put a rule in S0 before the
rule that sends host.domain to the tcp mailer to look for localhost.domain
and send it to the local mailer.

Fred