Herein lies the problem. We have users outside of the college who are
using an ISP which blocks port 25. Our mail server does not support
port 587, at least that I am aware of. This means we cannot use smtp
auth or use sasl over port 587.
stuart(_at_)bmsi(_dot_)com 4/14/2005 3:59:17 PM >>>
On Thu, 14 Apr 2005, Andrew Gutkowski wrote:
would not send it back to our smtp agent. In fact, wouldn't this
make
thigs worse. The ISPs smtp agent would reject the mail because the
user
does not exist on that mail server. Please correct me if I am
understanding smtp_auth incorrectly.
The point of SMTP AUTH is that the users would connect to the college
servers *instead* of the ISP servers. The AUTH part ensures that only
authorized users can do so (so the college servers do not become
open relays). The point of using port 587 is that many ISPs block
outgoing
port 25 beyond the ISP to cut down on outgoing spam.
The same would apply to pop before smtp. The college's users are
connecting to the college's smtp agent to pop mail and then
connecting
to the ISPs smtp server to send mail.
Again, the users would connect to the college server to send mail,
and the POP authorization is kludgey way to authorize that and
prevent an open relay when SMTP AUTH can't be used for some reason.
The end result is that if your users want to send mail with a MAIL
FROM
domain of 'college.edu', they MUST use the smtp servers you designate.
If they
are outside the campus, they must use those servers via SMTP AUTH (on
port
587 in case the ISP blocks 25).
--
Stuart D. Gathman <stuart(_at_)bmsi(_dot_)com>
Business Management Systems Inc. Phone: 703 591-0911 Fax: 703
591-6154
"Confutatis maledictis, flamis acribus addictis" - background song for
a Microsoft sponsored "Where do you want to go from here?" commercial.
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