Javier Posted April 10, 2008 Share Posted April 10, 2008 It is supposed that mail servers should bounce NDR's to local users only (or so I have been told). So I have been making some checking about my actual ISP behavior regarding this matter, and I have got mixed results that don't fit with the ones expected (by me). I will be grateful if you let me know if -as I think- my ISP have a wrong configuration (or not entirelly desirable), or it is me and my assumptions the ones that are wrong. - The first check I have made is to send a email (with "me[at]myISP.com" in the 'From' field) to an address that I know for sure that it don't exist (let's call it "notexist[at]otherdomain.xyz"), via my ISP mail server. As expected, the otherdomain.xyz mail server sent a 550-error to myISP.com server, and then myISP.com server bounced it to me[at]myISP.com: ... <notexist[at]otherdomain.xyz>: host mail.otherdomain.xyz[xxx.xxx.xxx.xxx] said: 550 5.1.1 <notexist[at]otherdomain.xyz>: Recipient address rejected: User unknown in virtual mailbox table (in reply to RCPT TO command) ... Until here, all correct (or I think so). - The second check, I sent the same email to notexist[at]otherdomain.xyz via my ISP mail server, but I changed the 'From' field to "me[at]elsewhere.com" (a discardable email got on purpose). I was expecting that my ISP received the 550-error, and after realizing that me[at]elsewhere.com wasn't a local user, it simply discarded/deleted the bounce. Instead of it, my ISP mail server bounced the NDR to me[at]elsewhere.com: Return-path : <> Envelope-to : me[at]elsewhere.com Delivery-date : Thu, 10 Apr 2008 12:47:41 +0200 Received : from [192.168.1.55] (helo=antimisp01) by mxb08.elsewhere.com with esmtp (Exim 4.68) id 1JjuJf-0008GB-Mf for me[at]elsewhere.com; Thu, 10 Apr 2008 12:47:40 +0200 Received : from smtp01.myISP.com ([xxx.xxx.xxx.xxx]) by antimisp01 with elsewhere id Bmnf1Z0063g5D2u0000000; Thu, 10 Apr 2008 12:47:39 +0200 Received : from exim by smtp01.myISP.com with local (Exim 4.60) id 1JjuJW-0005j9-CT for me[at]elsewhere.com; Thu, 10 Apr 2008 12:47:30 +0200 X-Failed-Recipients : notexist[at]otherdomain.xyz Auto-Submitted : auto-replied From : Mail Delivery System <Mailer-Daemon[at]smtp01.myISP.com> To : me[at]elsewhere.com Subject : Mail delivery failed: returning message to sender Message-Id : <E1JjuJW-0005j9-CT[at]smtp01.myISP.com> Date : Thu, 10 Apr 2008 12:47:30 +0200 X-Virus-Scanned : by elsewhere.com This message was created automatically by mail delivery software. A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. The following address(es) failed: notexist[at]otherdomain.xyz SMTP error from remote mail server after RCPT TO:: host mail.aafg.es [xxx.xxx.xxx.xxx]: 550 5.1.1 : Recipient address rejected: User unknown in virtual mailbox table ------ This is a copy of the message, including all the headers. ------ <snip> Original message <snip> Is this behavior correct? (to bounce the 550 to an address -me[at]elsewhere.com- external to the server receiving it -myISP.com-)? Shouldn't instead be deleted the 550-error message, without further bounces? Link to comment Share on other sites More sharing options...
This topic is now archived and is closed to further replies.