> > Upon receipt of mail at the end of the DATA portion > > of the SMTP transaction, look at the mail envelope > > (and possibly the From: header) and parse out the > > domain name that the mail is supposedly sent from. > > Then, look up the DNS for that domain name, looking > > for IN MX records. > > I wrote a sendmail milter that does that. You give it list of > major spam domain names and what thier legal mx hosts are and if > they don't match, it's rejected. You could also wildcard certain > mx's like *modem* dsl*.* etc
You want to be careful, because not everyone has this set up correctly. The mx check is one of the many that ActiveState's PureMessage uses, but it does it amongst 100s of other rules and a weighting system (where you can even include negative scoring). That way I still get the mail from a couple of people who have suffered at the hands of bad ISPs and get their mx records botched every 3 months. Jeff Hobbs The Tcl Guy Senior Developer http://www.ActiveState.com/ Tcl Support and Productivity Solutions -- AOLserver - http://www.aolserver.com/ To Remove yourself from this list, simply send an email to <[EMAIL PROTECTED]> with the body of "SIGNOFF AOLSERVER" in the email message. You can leave the Subject: field of your email blank.
