Exchange 2010 not receiving emails from some senders. They receive the following email rejection message:

Diagnostic information for administrators: Generating server: mail.domain.com.au [email protected] #< #4.4.7> #SMTP#

I enabled protocol logging on the receive connector. I cannot see any errors, however the problem emails appear to get cut short with "250 CHUNKING" being the last log entry (no DATA log entry).

2014-10-03T05:09:45.554Z,MAIL\Receive Connector,08D1ACCDF829605D,0,,123.456.789.123:44347,+,,
2014-10-03T05:09:45.554Z,MAIL\Receive Connector,08D1ACCDF829605D,1,,123.456.789.123:44347,*,SMTPSubmit SMTPAcceptAnySender SMTPAcceptAuthoritativeDomainSender AcceptRoutingHeaders,Set Session Permissions
2014-10-03T05:09:45.555Z,MAIL\Receive Connector,08D1ACCDF829605D,2,,123.456.789.123:44347,>,"220 mail.otherdomain.com.au Microsoft ESMTP MAIL Service ready at Fri, 3 Oct 2014 15:09:45 +1000",
2014-10-03T05:09:45.574Z,MAIL\Receive Connector,08D1ACCDF829605D,3,,123.456.789.123:44347,<,EHLO mail.domain.com.au,
2014-10-03T05:09:45.574Z,MAIL\Receive Connectorl,08D1ACCDF829605D,4,,123.456.789.123:44347,>,250-mail.otherdomain.com.au Hello [123.456.789.123],
2014-10-03T05:09:45.575Z,MAIL\Receive Connector,08D1ACCDF829605D,5,,123.456.789.123:44347,>,250-SIZE 10485760,
2014-10-03T05:09:45.575Z,MAIL\Receive Connector,08D1ACCDF829605D,6,,123.456.789.123:44347,>,250-PIPELINING,
2014-10-03T05:09:45.575Z,MAIL\Receive Connector,08D1ACCDF829605D,7,,123.456.789.123:44347,>,250-DSN,
2014-10-03T05:09:45.575Z,MAIL\Receive Connector,08D1ACCDF829605D,8,,123.456.789.123:44347,>,250-ENHANCEDSTATUSCODES,
2014-10-03T05:09:45.575Z,MAIL\Receive Connector,08D1ACCDF829605D,9,,123.456.789.123:44347,>,250-STARTTLS,
2014-10-03T05:09:45.575Z,MAIL\Receive Connector,08D1ACCDF829605D,10,,123.456.789.123:44347,>,250-AUTH,
2014-10-03T05:09:45.575Z,MAIL\Receive Connector,08D1ACCDF829605D,11,,123.456.789.123:44347,>,250-8BITMIME,
2014-10-03T05:09:45.575Z,MAIL\Receive Connector,08D1ACCDF829605D,12,,123.456.789.123:44347,>,250-BINARYMIME,
2014-10-03T05:09:45.575Z,MAIL\Receive Connector,08D1ACCDF829605D,13,,123.456.789.123:44347,>,250 CHUNKING,

Telnet test to port 25 from the sending mail server loses connection.

telnet port 25 connection to host lost

  • I suspect you're not going to be able to solve this w/o a packet capture of a real conversation between the sending mail server and your receiving server. Is that something you can get and update the question? Oct 6, 2014 at 23:49
  • I literally just resolved this issue by moving the inbound SMTP over to a different internet connection, plus setting a reverse DNS with the ISP.
    – Ash
    Oct 7, 2014 at 0:54
  • @Ash Would you please write it as an answer and then mark it as one, so your question won't appear as 'unanswered'?
    – EliadTech
    Oct 30, 2014 at 6:43

1 Answer 1


I literally just resolved this issue by moving the inbound SMTP over to a different internet connection, plus setting a reverse DNS with the ISP.

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