According to Q297412, the Exchange "Perform Reverse DNS Lookup for Incoming Messages" option does not block spam. Read this excerpt: - - - - - - - - Some messaging systems verify the existence of the e-mail domain of the sender before they accept a "Mail from: [EMAIL PROTECTED]" Simple Mail Transfer Protocol (SMTP) entry at the beginning of a new message delivery session. If the domain name cannot be resolved by means of Domain Name System (DNS), the session is disconnected and an error 501 is generated. This behavior is mainly used to prevent you from receiving spam (unsolicited e-mail messages). Neither Microsoft Exchange Server 5.5 nor Exchange 2000 use this feature. In Exchange 2000 System Manager, the "Perform Reverse DNS Lookup for Incoming Messages" option does not have the same function of the feature that had been previously described (the function to prevent the receipt of spam e-mail messages). When the preceding option is used, Exchange Server performs a DNS query to resolve the originating Internet Protocol (IP) address of the incoming messages to a host name. Then, the host name is attached to the headers of e-mail messages. - - - - - - - -
So it sounds to me like reverse DNS lookup to block spam would need to be done on some SMTP forwarding app or gateway outside Exchange. I probably don't understand this issue well enough, but I too would like to block spam, and am reluctant to get into 3rd-party filtering SW. - Bob Peitzke -----Original Message----- From: Sasha Kipervarg [mailto:[EMAIL PROTECTED]] Sent: Thursday, January 10, 2002 5:22 PM To: MS-Exchange Admin Issues Subject: RE: best-practice document explaining how to prevent spam msgs? Jesse, one thing you can do is enable reverse-lookups for any mail host that is delivering mail to you. This will slow down your server a bit and cause a bit more traffic, but it should block some of that spam. Not the best solution by a long shot, but it's at least something. tx, Sasha -----Original Message----- From: Jesse Rink [mailto:[EMAIL PROTECTED]] Sent: Thursday, January 10, 2002 7:59 AM To: MS-Exchange Admin Issues Subject: best-practice document explaining how to prevent spam msgs? Alright. We do not have any content filtering software on our Exchange server at this time. As most Exchange admins are aware, content filtering software can cause just as many headaches after it's been installed prior to it being installed at all. The best way to prevent unwanted spam seems to be for users NOT to give out their email address over the web (surveys, etc.), not to sign up for newsletters, not to do online ordering, and other obvious things. I'm wondering if there's a document out there that someone has used that explains these things in detail? Basically a "How to prevent unwanted email - faq" or something like that that I can send out to our users... Any idea? List Charter and FAQ at: http://www.sunbelt-software.com/exchange_list_charter.htm List Charter and FAQ at: http://www.sunbelt-software.com/exchange_list_charter.htm List Charter and FAQ at: http://www.sunbelt-software.com/exchange_list_charter.htm
