Complete sendmail newbie here... I've been trying to get mailing to work in PHP and I've root caused it down to sendmail's complaint about "Name server timeout":
>sendmail -t -v >From: email@example.com >To: firstname.lastname@example.org >. gmail.com: Name server timeout email@example.com... Transient parse error -- message queued for future delivery firstname.lastname@example.org... queued
So it sounds like a DNS issue? But I can do a "dig mx gmail.com" and it will query successfully.
Here's what confuses me... I can get sendmail to work two other ways. The first way is through telnet:
>telnet 127.0.0.1 25 >Helo me >Mail from: email@example.com >Rcpt to: firstname.lastname@example.org >. message sent
And the second way is by explicitly appending the sendmail.cf, but this is strange because it's the exact same file I use to configure sendmail to begin with:
>sendmail -t -v -C/etc/mail/sendmail.cf
But none of these solutions will resolve my PHP mailing... I am clueless as to what is going on... appreciate any help.