It was the backscatter filters in Forefront Protection for Exchange 2010 ... we left it flipped on on one of the transport servers, messages that got routed through its queue would fail foreign sender-verification routines.
I guess if you have that flipped on, the prvs tags that get pre-pended to the user email addresses cause some sender-verification vendors to fail on an otherwise valid sender. From: Michael B. Smith [mailto:mich...@smithcons.com] Sent: Wednesday, September 29, 2010 12:49 PM To: MS-Exchange Admin Issues Subject: RE: prvs verification errors, exch2010/2003 coexistence environment outbound I know nothing about sender verification, but my first step would be to look at the smtp-sender logs to see what is being handed off to the remote server. Regards, Michael B. Smith Consultant and Exchange MVP http://TheEssentialExchange.com From: Rick Berry [mailto:rbe...@elevativenetworks.com] Sent: Wednesday, September 29, 2010 12:11 PM To: MS-Exchange Admin Issues Subject: prvs verification errors, exch2010/2003 coexistence environment outbound I'm getting messages bounced outbound, sender verification stuff I'm not entirely familiar with ... redacted snippet follows. I had always associated the 'prvs' stuff with sender verifcation stuff and also Forefront backscatter filters, which I've disabled on the two hub transport Exch2010 boxes (and restarted msexch tranport service) <snip> remote.server.ru rejected your message to the following e-mail addresses: em...@email.com<mailto:em...@email.com> mx3.z8.ru gave this error: Verification failed for <prvs=5887211ea1=u...@user.com<mailto:prvs=5887211ea1=u...@user.com>> Called: *.*.*.* Sent: RCPT TO:<prvs=5887211ea1=u...@user.com<mailto:prvs=5887211ea1=u...@user.com>> Response: 550 5.1.1 User unknown Sender verify callout failed [#1005]. See http://blah.blah.ru/mailerrors/#1005 for details. A problem occurred during the delivery of this message to this e-mail address. Try sending this message again. If the problem continues, please contact your helpdesk. </snip> It's as though the remote servers are trying to verify that my users are indeed valid senders from user.com, somewhere the prvs=blah is getting prepended to the string and evil ensues. Not sure where to go to figure this one out, aside from cracking open a PSS case and crossing my fingers. another snippet, just in case. mail-mx-00.blah.nl gave this error: Verification failed for <prvs=6887e68943=u...@user.com<mailto:prvs=6887e68943=u...@user.com>> Called: *.*.143.134 Sent: RCPT TO:<prvs=6887e68943=u...@user.com<mailto:prvs=6887e68943=u...@user.com>> Response: 550 5.1.1 User unknown Sender verification error (recipient) for prvs=6887e68943=u...@user.com<mailto:prvs=6887e68943=u...@user.com> where u...@user.com<mailto:u...@user.com> = a valid email address in our system. --- To manage subscriptions click here: http://lyris.sunbelt-software.com/read/my_forums/ or send an email to listmana...@lyris.sunbeltsoftware.com<mailto:listmana...@lyris.sunbeltsoftware.com> with the body: unsubscribe exchangelist --- To manage subscriptions click here: http://lyris.sunbelt-software.com/read/my_forums/ or send an email to listmana...@lyris.sunbeltsoftware.com<mailto:listmana...@lyris.sunbeltsoftware.com> with the body: unsubscribe exchangelist --- To manage subscriptions click here: http://lyris.sunbelt-software.com/read/my_forums/ or send an email to listmana...@lyris.sunbeltsoftware.com with the body: unsubscribe exchangelist
