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451 Backend Replied 4.7.0 Timeout waiting for client = Not receiving _some_ external eMail, Internal receipts ok RRS feed

  • General discussion

  • Does anyone know if this error message indicates the message is not entering our gateway due to MTU size?  Or is it something else?  Please give any information you are aware of.  With many thanks, Coquette4

    451 Backend Replied 4.7.0 Timeout waiting for clien

    I will continue trying to send the message until it is delivered

    • Changed type Coquette4 Thursday, August 23, 2012 7:07 PM Need Help fixing issue.
    Thursday, August 23, 2012 6:01 PM

All replies

  • You're not receiving all external email? Do some eventually come in but is delayed? Where did you get this NDR message? Does exchange receiving internet mail directly or you have a gateway smtp server? Seems like you are greylisting\throttling\tarpitting them, or possibly a firewall\proxy is preventing bdat chunking. Check your smtp logs.

    James Chong MCITP | EA | EMA; MCSE | M+, S+ Security+, Project+, ITIL msexchangetips.blogspot.com


    Thursday, August 23, 2012 6:13 PM
  • Thank you.  Will do.
    Thursday, August 23, 2012 7:16 PM