I upgraded from Ubuntu Server 10.04 to 12.04. Now my php sites are no longer sending mail. When I went in to look at the sendmail mail queue, all of my messages were there.
When I try to force the queue with debugging (sendmail -v -q), I get the following response.
(actual names masked for privacy/security)
Running /var/spool/mqueue/r7KC82jb030432 (sequence 19 of 19)<firstname.lastname@example.org>... Deferred: Connection refused by server.domain.local.domain.com.
Our SMTP mail server is server.domain.local. How do I get rid of the .domain.com?