On Wed, 1 Dec 2021 at 20:25, Ariel Burton via talk <talk@gtalug.org> wrote:

Hi everyone,

I'm trying to get outgoing SMTP email to work with Rogers,
and would appreciate any help.

/home/me> mail MY-OTHER-EMAIL-ADDRESS
Subject: test
test
.
EOT
% smtp-server: 550 Request failed; Mailbox unavailable
"/home/me/dead.letter" 12/365
. . . message not sent.

As a starting point, I would suggest using the "-v" switch to enable verbose mode. Then you will see the details of the actual message delivery and protocol conversations which may provide you some hints about what's going on.