On Thu, Aug 27, 2009 at 10:06:03AM -0500, Shawn McKenzie wrote: > Paul M Foster wrote: > > On Thu, Aug 27, 2009 at 09:00:24AM -0400, Bob McConnell wrote: > > > >> The return code only tells you the local server accepted the mail. It is > >> unlikely that server knows the address is invalid since it can only > >> validate the domain portion of the address. Only the destination server > >> can validate the user name, and most are now configured not to report > >> mail sent to invalid addresses due to spam. They will silently discard > >> the message. > >> > > > > It used to be that internet mail servers would deny an email address as > > invalid while the SMTP conversation was going on. Then, because of > > services with millions of addresses, like Yahoo, they stopped doing > > this, and instead would bounce the messages back some time later. > > > > I recently had a conversation with a guy who's heavily involved in > > internet email. His view echoed what you're saying-- it does spammers a > > favor to bounce messages to bad addresses. But I got the impression that > > his view was a minority one. > > > > It sounds like you're saying his view has become the majority view. Does > > your job put you in a position to confirm this with authority? > > > > Paul > > > > It's called backscatter spam and the problem is this: if a spammer uses > someones legitimate address, let's say yours as the from address, and > sends to thousands of recipients, then you get all of the failure > messages. If that's not bad enough, consider if the from address is a > legitimate domain but nonexistent user, then the server that receives > the failure messages sent to the nonexistent user may issue its own > failure messages back to the other nonexistent users, and maybe back and > forth either infinitely or until some server reaches a configured > threshold of some sort. Believe me, I know about backscatter. I'm admin on about six lists, and my email address is on at least five public websites. You want backscatter? I got backscatter. The worst case (not necessarily backscatter) was when I had a backup admin on one of those lists, and majordomo was issuing bounces to both the backup and me. Unfortunately, at the same time, his email address went down. Now I was getting bounces of the bounces from his email address too. And each email contained the text of the previous bounce. So I was getting 250k (size) emails (and growing) as fast as majordomo could generate them. I had to call the host company for the lists to get them to take him off as an admin. I just love computers. ;-} Paul -- Paul M. Foster -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
