When I re-installed Debian, I neglected to create a ‘postfix’ user locally and so postfix wasn’t starting up. This meant that any application that tried to send mail using the local mail agent (as opposed to using mail.eskimo.com) would not have succeeded.
This has been corrected.
I am still re-installing software on Debian. If anything you need is missing please let me know and I’ll bump it to the top of the priority stack.