the claim is that outbound 25 is blocked to prevent spam. however
accessing a remote 25 with smtpauth ensures full accountability and,
therefore, prevents spam. blocking 25 disables use of this mechanism.
> 3. SMTPAUTH does not require an alternate port, yet it is sufficient for
> ensuring accountability. Hence it is sufficient for dealing with the
> reason that port 25 is blocked, without requiring that it be blocked.
I don't understand this reasoning. The ISP's justification for blocking
25 except to its own servers is to avoid having its facilities used
for abuse. How would the local ISP enforce use of SMTPAUTH to connect
to some remote ISP?