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zmailer syntax error code

It seems smtpserver returns 550 instead of 500 on syntax error (e.g. response
to EHLO by an smtpserver without ESMTP support).  As I read RFC821, 500 is
more appropriate (although 550 is not necessarily wrong).  Worse, RFC1869
assumes a non-ESMTP smtpserver will return 500, not 550, and if an ESMTP
client gets 550 as a response to EHLO, QUIT is as legitimate a response from
the connecting client as HELO, at least as I read section 4.4 of RFC1869.  Of
course, most clients choose to issue an HELO, but I've heard of one that does
a QUIT -- and I can't point to the RFC and say it's doing the wrong thing.

This is less of an issue for ESMTP versions of smtpserver like Matti's,
since it knows what to do with EHLO, but the zmailer running on nic.funet.fi
still returns 550 to a syntax error, rather than 500.

I've fixed the smtpserver we use; I encourage other users/maintainers of
zmailer to do the same.


John DiMarco <jdd@cs.toronto.edu>                         Office: SF2101
CSLab Systems Manager                                     Phone: 416-978-5300
University of Toronto                                     Fax:   416-978-1931