> It's more an error in configuration. These days, sending back an entire > message in a bounce is most unfriendly, since it's so likely to distribute a > virus to an innocent third party. We cut off our bounce messages at--I > think--10K. Newer Exims (I forget the transition point) can also be > configured not to return the body at all).
Yes, that is preferential, although I hope it still returns headers or at least the IP address of the incoming message. Yet this doesn't matter in the case where a 550 User Unknown error is generated. The entire SMTP transaction is briefly... HELO< 250>, MAIL FROM< 250 OK>, RCPT TO< 550 Unknown User>, QUIT. No DATA so the message that caused the bounce is irrelevant. This is less of a problem although there is no reason for the Exim server to retry this 27 times over the next few days. >> Here is the problem, the Exim servers will retry to resend the message >> (ignoring the 55x errors) every two hours for 2 or 3 days. The >> bounce's message-id, date, other headers, and the quoted forgery all >> demonstrate that the multiple bounces are caused by a single message >> and the multiples are a result of a problem with Exim not >> acknowledging my server's 55x responses. Normally this problem >> wouldn't be noticed as bounces aren't normally seen. > > In my experience, Exim doesn't do that, and I'm not quite sure what I would > do to cause it. I can get you a list of Exim servers from my logs which seem to do this. Poeple on this list are even less likely to experience this as their Exim servers may accept problem messages in the first place and filter them immediately. To duplicate this, authenticate or otherwise use your Exim server to relay a message to a non-local account that generates a 550 User Unknown error. 1. In DNS, configure the mx sub.yourdom.com to point to any foreign mail server (like mx1.hotmail.com or whatever). 2. Send a message to your Exim server from <[EMAIL PROTECTED]> to <[EMAIL PROTECTED]> using authentication or from a local/known IP address so it acts as a relay. Once accepted the trap is set. Your Exim server will try to deliver the message to the foreign host and get a 550 user unknown or 550 we do not relay for <[EMAIL PROTECTED]> (or in the case of hotmail, 550 Requested action not taken: mailbox unavailable). Then it should try to send a bounce from <> to <[EMAIL PROTECTED]>, if that message remains in the queue after the first attempt then we've duplicated the problem. This is only a few seconds after we've sent the message. Just to ensure, this wasn't a problem with my server or it's software as opposed to the half dozen or so examples of different Exim servers that I've quickly found in my logs. I've just gone through the trouble (2 minutes) of setting up the SMTP service on a new server to debug this. I took a test Windows 2003 box setup the SMTP service (my main server doesn't use MS mail software so different server/different mail server software) and opened the smtp port. With no mailboxes and nothing else setup, now any message sent to that machine will get a 550 Unable to relay for <whomever>. I needed to test this against a foreign server so I setup a public MX for test.tymes.net to forward to this server (which still won't accept it). That servers logs will indicate when the remote server tries to connect and deliver a bounce. I sent off the seed message from a bogus address <[EMAIL PROTECTED]> to test an Exim server (sorry, but they have already sent me 27 virus infected messages) and two hours later, I got a second bounce so this will presumably continue for the next few days as that remote Exim 4.50 server tries to deliver the bounce. Someone with their own Exim server wouldn't haven't to wait two hours as they would just be able to look in the Outgoing queue to see if the bounce was still there after the first attempt. Here is a snipt from the SMTP logs of the server I setup. 2005-06-07 19:47:31 69.72.225.186 bob.xstreamhost.com EHLO - +bob.xstreamhost.com 250 0 182 24 16 SMTP - - - - 2005-06-07 19:47:31 69.72.225.186 bob.xstreamhost.com MAIL - +FROM:<> 250 0 27 22 0 SMTP - - - - 2005-06-07 19:47:31 69.72.225.186 bob.xstreamhost.com RCPT - +TO:<[EMAIL PROTECTED]> 550 0 57 35 0 SMTP - - - - 2005-06-07 19:47:31 69.72.225.186 bob.xstreamhost.com DATA - - 554 0 0 4 0 SMTP - - - - 2005-06-07 19:47:31 69.72.225.186 bob.xstreamhost.com QUIT - bob.xstreamhost.com 240 375 53 4 0 SMTP - - - - 2005-06-07 21:31:38 69.72.225.186 bob.xstreamhost.com EHLO - +bob.xstreamhost.com 250 0 182 24 0 SMTP - - - - 2005-06-07 21:31:38 69.72.225.186 bob.xstreamhost.com MAIL - +FROM:<> 250 0 27 22 0 SMTP - - - - 2005-06-07 21:31:38 69.72.225.186 bob.xstreamhost.com RCPT - +TO:<[EMAIL PROTECTED]> 550 0 57 35 0 SMTP - - - - 2005-06-07 21:31:38 69.72.225.186 bob.xstreamhost.com DATA - - 554 0 0 4 0 SMTP - - - - 2005-06-07 21:31:38 69.72.225.186 bob.xstreamhost.com QUIT - bob.xstreamhost.com 240 437 53 4 0 SMTP - - - - -- ## List details at http://www.exim.org/mailman/listinfo/exim-dev Exim details at http://www.exim.org/ ##
