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451 Temporarily unable to process your email. Please try again later.

Discussion in 'E-mail Discussions' started by Legin76, Nov 12, 2015.

  1. Legin76

    Legin76 Well-Known Member

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    Hi

    One of my servers appears to be bouncing some incoming emails with the error "451 Temporarily unable to process your email. Please try again later. (in reply to RCPT command)".

    It appears to be a bit random.. Some emails from the same sender will be received but others will bounce.

    I'm sure I've seen a setting that does something similar to this but can't find it now.

    CENTOS 6.7 x86_64 xenpv – WHM 11.52.1 (build 0)
     
    #1 Legin76, Nov 12, 2015
    Last edited: Nov 12, 2015
  2. cPanelMichael

    cPanelMichael Forums Analyst
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    Hello :)

    You can review /var/log/exim_mainlog to determine the exact reason for the failure. EX:

    Code:
    exigrep user@domain /var/log/exim_mainlog
    Thank you.
     
  3. Legin76

    Legin76 Well-Known Member

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    It appears to be something to do with the grey listing...

    2015-11-11 10:51:18 H=ftx-008-i765.relay.changedname.net [01.12.345.67]:7912 X=TLSv1.2:DHE-RSA-AES256-GCM-SHA384:256 CV=no F=<email@domain.co.uk> temporarily rejected RCPT <email@receivingaddress.co.uk>: Deferred due to greylisting. Host: '01.12.345.67' From: 'email@domain.co.uk' To: 'email@receivingaddress.co.uk' SPF: 'unchecked'

    2015-11-11 11:00:28 H=ftx-008-i771.relay.changedname.net [01.12.345.67]:14402 X=TLSv1.2:DHE-RSA-AES256-GCM-SHA384:256 CV=no F=<email@domain.co.uk> temporarily rejected RCPT <email@receivingaddress.co.uk>: Deferred due to greylisting. Host: '01.12.345.67' From: 'email@domain.co.uk' To: 'email@receivingaddress.co.uk' SPF: 'unchecked'
     
  4. Legin76

    Legin76 Well-Known Member

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    The Greylisting settings are as follows..


    Deferral Period (in minutes)
    10

    Resend Acceptance Period (in minutes)
    240

    Record Expiration Time (in minutes)
    4320

    Bypass Greylisting for Hosts with Valid SPF Records
    Un-checked
     
  5. cPanelMichael

    cPanelMichael Forums Analyst
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    Hello :)

    The logs indicate the second retry attempt was before the 10 minute deferral period. You can reduce the deferral period if you want to accept emails that are resent at a shorter duration:

    Greylisting - Documentation - cPanel Documentation

    Thank you.
     
  6. Legin76

    Legin76 Well-Known Member

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    I've reduced it to 5 minutes although it appears that the IP is different for each send attempt.

    I thought the greylist bounce message was one that went to the server so it would retry and not to the sender.

    Would turning on "Bypass Greylisting for Hosts with Valid SPF Records" help?
     
  7. cPanelMichael

    cPanelMichael Forums Analyst
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    Yes, you can enable that option if you want to allow email from hosts with valid SPF records to skip the greylisting functionality.

    Thank you.
     
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