I would like to know of any advantages/disadvantages of using an smtp relay (with sendmail/postfix/qmail) over using a programming language's built-in smtp api.
We have always run a mail server off of the same box that runs our web app, so it has always been pretty simple for us to send email, whether it be with PHP or Python or whatever - no worries about network outages or anything like that disrupting emails since the mta is pretty reliable. Now that we are switching to use Google Apps for email, the email needs to go through the gmail smtp server, so I am deciding if I should use the programming language-specific apis that support sending smtp mail, or if I should setup a smtp relay on the server (with postfix, for example) so that the app can continue to send mail with the reliability of a local mta.
It would be great if you could identify advantages/disadvantages of each approach.