On Sat, 11 Jan 2003, Claudio Jeker wrote: > On Sat, Jan 11, 2003 at 04:03:26PM +0200, Taymour A. El Erian wrote: > > > > I can't understand the feature badmailfrom-unknown, does it mean it won't accept > > any messages from any server/sender without PTR ? > > > > Yes, it means does the same things as the badmailfrom file but is only > used if there is no PTR record. So you can e.g. put hotmail.com in > badmailfrom-unkown and kill with that a lot of spam.
If you do this will normal hotmail.com mail make it through? For example, Normal, non-spam hotmail.com coming from a hotmail mail server will have a MAIL FROM envelope of [EMAIL PROTECTED] The IP of the connection will also have a PTR record of mailhost.hotmail.com. mailhost.hotmail.com will have an A record pointing back to the same IP. These match up so accept the mail SPAM on the other hand will have a MAIL FROM envelope of [EMAIL PROTECTED] and the IP *may* have a PTR record of mailhost.hotmail.com or mailhost.spammer.com or no PTR record. If it is a mailhost.hotmail.com PTR record there shouldn't be a valid A record for the host pointing to the same IP. This break should tell qmail to reject the mail. How is t his different from normal paranoia checks in tcpserver? Does this new feature handle the case where the spammer IP has proper forward and reverse DNS lookups on the IP. This will get past the paranoia checks. But if the MAIL FROM has *@hotmail.com the PTR must also have hotmail.com? This seems like it will break a lot of mail. Customers using my bandwidth MUST use my SMTP server. If they want the reply to go to their hotmail.com account the MAIL FROM envelope and From: header will contain [EMAIL PROTECTED] This is valid e-mail but would be broken in the above scenario. -Matt -- ---------------------------------------------------------------------- Matthew S. Crocker Vice President / Internet Division Email: [EMAIL PROTECTED] Crocker Communications Phone: (413) 746-2760 PO BOX 710 Fax: (413) 746-3704 Greenfield, MA 01302-0710 http://www.crocker.com ----------------------------------------------------------------------
