I'll use postfix for that case. For yet another point of view, how about using external SMTP server directly? You are sending messages as follows: app -> lo

I'll use postfix for that case. For yet another point of view, how about using external SMTP server directly? You are sending messages as follows: app -> local MTA -> /var/spool/mail <- users read mails but this is easier to setup: app -> gmail's SMTP server -> users