> -----Original Message----- > From: Pfefferkorn, Pete (PFEFFEPE) [mailto:[EMAIL PROTECTED]] > Sent: Friday, July 12, 2002 2:38 PM > To: Exchange Discussions > Subject: Reverse DNS and Exchange > > > Exchange 5.5 > > I'm a little confused on Reverse DNS. I kind of understand > the concept that > with Reverse DNS enabled the Mail from: entry must resolve to > a valid domain > or it will get rejected. Some I have some basic questions: > > I take it Exchange 5.5 does not support Reverse DNS?
Spot on. > How about Exchange 2000? Some enterprising folks may be able to write an event sink for this, I don't know. > How effective is Reverse DNS to help the control of Spam? Not very. A lot of spam comes through legitimate relays, and a lot of valid mail may come from places without Reverse DNS properly set up. In some cases, ISPs won't even set up reverse DNS properly for their customers. > What problems/issues will we encounter if we do implement > reverse DNS in > some for on front end servers whatever it may be? Can you rephrase this in the form of a question? > What about users who have POP and have their return address set to be > something other than their ISP but they use the ISP as the relay? Usually you check the HELO against the reverse DNS. So if the relay says HELO relay.company.com and the reverse DNS matches, no worries. > When they state the Mail From: they mean the From: in the > display area and > not all the routes? Often the From: is not checked there. > If you have a front end relay like PMDF/VMS which relays > first.last@domain > to a messaging system, reverse DNS will not prevent spam to > the receiving > systems since it will also validate from the relay? > Probably not. Reverse DNS A springtime admin's daydream Nice try, think again _________________________________________________________________ List posting FAQ: http://www.swinc.com/resource/exch_faq.htm Archives: http://www.swynk.com/sitesearch/search.asp To unsubscribe: mailto:[EMAIL PROTECTED] Exchange List admin: [EMAIL PROTECTED]
