Can you explain your criteria for accepting a sender if the host is not an MX for the domain? We have CanIT Pro and the mismatch rules tened to block alot of the "send the page to a friend" and e-card type emails. I had to give up on them (the mismatch rules, that is).
It looks like he's not checking that the sending server *is* an MX for the domain, (which would cause problems with sites that use separate servers for incoming and outgoing mail), but checking *an* MX to see if it recognizes the supposed sender's address.
The logic is more along the lines of:
- Sender claims to be [EMAIL PROTECTED]
- Look up MX records for speed.net
- Connect to mail.speed.net and see if it accepts mail for [EMAIL PROTECTED]
- From "User unknown" error, conclude that the sender is invalid and reject the message
In the old days, it might have been done using VRFY, but so many sites have disabled it to throw a roadblock in front of dictionary attacks.
Kelson Vibber
SpeedGate Communications <www.speed.net>
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