FYI:
I don't think this is a very well know. It seems that, on some operating systems, ActionMailer/SMTP crashes when it sends an email with only a '.' (aka a 'dot' or a 'period'). Specifically, you get Net::SMTPSyntaxError (502 Error: command not implemented):
Environment Details:
$ uname -a Linux private1 2.6.15-26-server #1 SMP Thu Aug 3 04:09:15 UTC 2006 i686 GNU/Linux
$ ruby --version ruby 1.8.4 (2005-12-24) [i686-linux]
$ rails --version Rails 1.1.6
Email Sending Details (example.com used in place of real data):
Sent mail: