If your SMTP server on Bell is failing to send mail from a web application with an obscure/misleading error like the following, just avoiding a foreign sender address (like @gmail.com) may solve.
This message was created automatically by mail delivery software.
A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:
foo@example.com
host smtp.bellnet.ca [204.101.251.122]
SMTP error from remote mail server after MAIL FROM:
452 4.1.0 requested action aborted:
try again later #AUP504: retry timeout exceeded