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NFR Wizards Archives: proxy firewall and email

proxy firewall and email

Subject: proxy firewall and email
From: Neil Ratzlaff (neil.ratzlaffucop.edu)
Date: Mon Jan 03 2000 - 16:48:34 CST

Caveat: I can give advice to the site in question, but I have no control
over it. The site admins are not very knowledgable about either their mail
server or firewall and consultants set it up for them.

I have a question about Raptor firewall and MS Exchange smtp server behind
it. The information below is to the best of my knowledge, but be aware I
know nothing about either Raptor or Exchange or NT. Together they seem to
create an open relay for spam.

The Raptor firewall accepts all mail and passes it to the smtp server for
delivery. If the recipient is not a valid user, the mail gets bounced by
the smtp server, but to the address in the From field, not to the sender or
last smtp server. Since you can put anything you want to in that field,
you can send spam via this relay, albeit perhaps slowly. The firewall does
not keep a list of legitimate users, so it can't reject mail as it should.

I am sure other places have dealt with this process, so how can I advise
this site to fix their setup? I would expect that Raptor should be able to
hook into Exchange to validate recipients, but the site admin tells me it
can't. I would be happy to tell them how to make Raptor just check that
the recipient domain is correct, which should be easy to check. A post
from the May99 archive of this list strongly suggests this is the correct
way to proceed.

Can anyone tell me how to explain to the site how to make this work?

Thanks,
Neil

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