Outside contacts at two companies report messages they sent to us return with the following message:

451 Timeout trying to verify RCPT validemail@ourdomain.com for domain

One of the companies is a very large international organization and so I doubt the issue is on their end, necessarily.

I understand this message generally means that my server is disconnecting before responding to the RCPT message from the other server.

I have an Exchange 2007 server and the first people reporting the issue (and the people I've been able to get a copy of the error message from) are running Lotus Domino (I do not recall my Domino support days fondly).

We also use an email backup service through DNSMadeEasy which handles all our incoming messages so that if our server loses contact with the internet for a while, the messages are all received and queued by DNSMadeEasy and upon establishment of the connection the messages are then delivered to us.

Things I have done:

  • Tested internal/external email communication using my personal external accounts and had no issues.
  • Verified I have no Anti-spam blacklisting configured in Exchange.
  • Checked my McAfee Groupshield logs and verified it did not reject any messages from these senders.

Where do I go from here?

Here is the full output (suitably obscured) from Lotus Notes regarding what it thinks the issue is (Sorry for the wall 'o text in the first part, I'm having trouble getting the lines to flow properly):

> Reporting-MTA: x-local-hostname; localdomain
> Authentication-Results: p01c11m085.mxlogic.net; spf=none X-MXL-Hash:
> 51ae20e2194675c6-9ab61e697b19b6b20a310d95e60b43dac243397d
> From: Mail Delivery System <MAILER-DAEMON@p01c11o143.mxlogic.net>
> To: TheirEmail@theirdomain.com
> Subject: Warning: could not send message for past 4 hours
> Message-Id: <mxl~0443.d62f.e8ee@p01c11o143.mxlogic.net>
> Date: Tue, 04 Jun 2013 11:16:10 -0600
> MIME-Version: 1.0
> X-MX-Bounce: mod_queue/warn
> X-AnalysisOut: [A:9 a=vypMwE87fLIA:10]
> Received-SPF: None
> X-Spam: [F=0.1384615385; B=0.500(0); spf=0.500; STSI=0.500(-49); STSM=0.300(-49); CM=0.500; MH=0.600(2013060409); S=0.200(2010122901); SC=]
> X-MIMETrack: Itemize by SMTP Server on TheirCompany-NT/TheirCompany(Release 6.5.1|January 21, 2004) at 06/04/2013 12:16:36 PM,
>                 Serialize by Router on TheirCompany-NT/TheirCompany(Release 6.5.1|January 21, 2004) at 06/04/2013 12:16:38 PM,
>                 Serialize complete at 06/04/2013 12:16:38 PM
> X-Notes-Item: CN=TheirCompany-NT/O=TheirCompany; type=501; flags=44; name=$UpdatedBy
> X-Notes-Item: 8EC07872:EEDBFA2A-86257B80:005EE789; type=4; name=$Orig X-Notes-Item: ; type=501; name=Categories
> X-Notes-Item: ; type=401; name=$Revisions
> X-Notes-Item: CN=TheirCompany-NT/O=TheirCompany; type=501; flags=0; name=RouteServers
> X-Notes-Item: 04-Jun-2013 12:16:36 CDT/04-Jun-2013 12:16:37 CDT; type=401; flags=0; name=RouteTimes
> X-Notes-Item: 0; name=$MsgTrackFlags
> X-Notes-Item: Tue, 4 Jun 2013 12:16:37 -0500; type=400; name=DeliveredDate
> X-Notes-Item: TheirCompany-NT/TheirCompany!!mail/theirnsf.nsf: =?UTF-8?B?4oChODYyNTcxNUQwMDUzNjc2Nyg=?= =?UTF-8?B?OEVDMDc4NzJFRURCRkEyQTg2MjU3QjgwMDA1RUU3ODkp?=; name=$SJOrigin
> X-Notes-Item: TheirEmail@theirdomain.com; name=$SJInternetAddress
> X-Notes-Item: MAILER-DAEMON@p01c11o143.mxlogic.net; name=$SJEmail
> X-Notes-Item: p01c11o143.mxlogic.net; name=$SJDomain Received: from p01c11m085.mxlogic.net ([]) by mail.theirdomain.com (Lotus Domino Release 6.5.1) with SMTP id 2013060412163648-12883 ; Tue, 4 Jun 2013 12:16:36 -0500 Received: from unknown [] (EHLO p01c11q162.mxlogic.net)                 by p01c11m085.mxlogic.net(mxl_mta-7.1.0-2) over TLS secured channel       with ESMTP id 2e02ea15.0.9233563.00-1301.13111517.p01c11m085.mxlogic.net (envelope-from <>);                 Tue, 04 Jun 2013 11:16:18 -0600 (MDT) Received: from unknown [] (EHLO p01c11o143.mxlogic.net)                 by p01c11q162.mxlogic.net(mxl_mta-7.1.0-3) over TLS secured channel       with ESMTP id 2e02ea15.0.9064.00-2396.25366.p01c11q162.mxlogic.net (envelope-from <>);                 Tue, 04 Jun 2013 11:16:18 -0600 (MDT) Received: FROM queue-bounce BY 01c11o143.mxlogic.net WITH local;                 Tue, 04 Jun 2013 11:16:10 -0600
> X-Notes-Item: Memo; name=Form
> X-Notes-Item: 1; name=$NoteHasNativeMIME Content-Type: multipart/report; report-type=delivery-status; boundary="Q=_941804289-1370366170-p01c11o143.mxlogic.net"
> This is a MIME-formatted message. Portions of this message may be unreadable without a MIME-capable mail program.
> --Q=_941804289-1370366170-p01c11o143.mxlogic.net Content-Type: text/plain
>      ===============================================
>              THIS IS A WARNING MESSAGE ONLY        
>      ===============================================
> A temporary error occurred while delivering to the following
> address(es):
>  <MyEmail@mydomain.com>: 451 Timeout trying verify RCPT
> (MyEmail@mydomain.com) for domain (mydomain.com)
> I will continue trying to send the message until it is delivered or
> expires.
> --Q=_941804289-1370366170-p01c11o143.mxlogic.net Content-Type: text/plain
> Included is a copy of the message header:
> ----------------------------------------- Received: from unknown [] (EHLO mail.theirdomain.com)
>                 by p01c11o143.mxlogic.net(mxl_mta-7.1.0-3)
>                 with ESMTP id ad5eda15.0.73070.00-330.174376.p01c11o143.mxlogic.net (envelope-from
> <TheirEmail@theirdomain.com>);
>                 Tue, 04 Jun 2013 07:05:26 -0600 (MDT) X-MXL-Hash: 51ade6163c8c4185-18c8ce3cbb57672918d5c615db6b50a5e7accd4d To:
> MyEmail@mydomain.com Subject: Fw: DELIVERY FAILURE: MIME-Version: 1.0
> X-Mailer: Lotus Notes Release 8.5.2 August 10, 2010 Message-ID:
> <OF52E79DBB.50860208-ON86257B80.0047C79E-86257B80.0047D1CD@theirdomain.com>
> From: TheirEmail@theirdomain.com Date: Tue, 4 Jun 2013 08:04:27 -0500
> X-MIMETrack: Serialize by Router on
> TheirCompany-NT/TheirCompany(Release 6.5.1|January 21, 2004) at
> 06/04/2013 08:05:26 AM,
>                 Serialize complete at 06/04/2013 08:05:26 AM Content-Type: multipart/alternative; boundary="=_alternative
> 0047D1CC86257B80_="
> --Q=_941804289-1370366170-p01c11o143.mxlogic.net--
  • Thanks for cleaning that up Micheal. I thought I did what you did, but apparently I was missing something. – music2myear Jun 7 '13 at 14:21

The best way would be to work on that issue together with the remote company. They can check there logs while you can check your logs. If your Server really caused an timeout they might quickly adjust the MailTimeout value on there side as mentioned here. So if this setting is on 4 hours (as it looks like currently) they can change that to 8 hours. They also can enable the SMTP debugging on there side to check whats going on.

| improve this answer | |
  • Thanks for the answer @BastianW. I have moved on to greener pastures since this error and at this point cannot actually recall what resolved the issue. I'm guessing people stopped complaining and I moved on to other fires. – music2myear Nov 14 '16 at 17:09
  • sure just found that wile I was troubleshooting a similar issue and thought I might wish to leave some solution for others which might see that one as well :). If you are happy with the solution can you maybe accept that as answer ;-). – BastianW Nov 14 '16 at 17:45

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