in reply to Mail::Sendmail or NET::SMTP
The last time I saw Mail::Sendmail, I believe that it required me to edit path to my sendmail binary in the .pm file. I really didn't like that. Not sure what's happened with it since those days.
I use Net::SMTP for most mailings these days. I didn't know that it was RFC compliant, but that's because I haven't really read the docs on it. The POD has an example at the top that has satisfied all of my needs thus far. Net::SMTP is an excellent module and does its job well.