Using Mutt with Exim4 to Send Mail via Smarthost over SSL (TLS) Connection on Port 465
One day I’ll learn pine and I’m sure I’ll love it but for now I’m hooked on mutt.
Getting mutt to use exim4 for delivery is as simple as adding set sendmail="/usr/sbin/exim4" to your ~/.muttrc. Getting exim4 working as a smarthost to authenticate over port 465 is far harder.
The solution is to use a tunnel as outlined in this excellent post: exim4 with ssmtp on Debian.
Before finding this answer, I also discovered a very clear post on testing an smtp auth connection here and a useful tutorial on setting up and testing exim, both of which may be helpful to other people.