I'm having a weird and frustrating problem. With identical code, I can send mail from one of my apps but not another. Here's
/var/log/mail.log for the e-mail that works:
Nov 9 17:12:23 gob sm-mta: oA9MCN6H006693: from=<email@example.com>, size=612, class=0, nrcpts=1, msgid=<firstname.lastname@example.org>, proto=ESMTP, daemon=MTA-v4, relay=localhost.localdomain [127.0.0.1] Nov 9 17:12:24 gob sm-mta: oA9MCN6H006693: to=<email@example.com>, delay=00:00:01, xdelay=00:00:01, mailer=esmtp, pri=120612, relay=gmail-smtp-in.l.google.com. [18.104.22.168], dsn=2.0.0, stat=Sent (OK 1289340744 ga18si18104172ibb.16)
And here's the log for the one that doesn't work:
Nov 9 17:13:03 gob sm-mta: oA9MD3dp006704: localhost.localdomain [127.0.0.1] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA-v4
Same machine, same code (at least for the e-mail sending part). I can't figure out why one works and the other one doesn't.
(P.S. There's some overlap, but I figure this is more of a sysadmin question that a programming question, plus the person who knows the answer is more likely to be here than at Stack Overflow.)