Need Help - Spam Prevention Server - Virtual MX Records/SMTP/POP3

[Mike Curry]

I am creating a spam prevention server for a mail hosting company using
Windows 2000 SMTP Sinks. Basically the end users (www.theenduser.com)
changes their MX servers to point to our server so the mail comes to us.
When we receive mail we keep the mail in a pending/non-verified folder. At
this time we send a email to the mail sender asking them to confirm that
they sent a message. Once they verify the email, we forward it on to the
real www.theenduser.com's domain.

My question is, how do I forward the email to the domain if their MX records
are pointed to us? Can we send the email to their SMTP server manually?
How would we go about doing this? Whats the best way to do this?

Can I create a local "hosts" file with the true domain smtp server? Help!

 

[Anon-E-Moose]

Once they verify the email, we forward it on to the
real www.theenduser.com's domain.

My question is, how do I forward the email to the domain if their MX
records are pointed to us?

In esscence your server has become a gateway - so the enduser has no MX
record anymore (or a MX record with a higher prefernce). You'll need to
keep an internal look up table with the IP address of the end users real
mail server. Once you have the IP, just connect directly (via IP) and send
the message as usual. Even tho the end user has no MX record, the mail
server will accept the message as long as the domain is listed as a valid
one on the server.


Or as stated before, maybe you can ask the end users to raise the
preference of their real mail server and add the spam server as preference
0. All mail will be channelled to the spam server unless it has crashed in
which case mail will be sent directly to the end users mail server. This
way should your service go down, the end user won't lose mail.