Hi,
I have posted this in the german forum some days ago (Thread-ID e874f5d8-8fcd-4831-b60a-5cb6ac37d752, sorry can't post links), but the problem seems to be very specific.
Our Exchange 2010 is unable to send a mail to one specific server. The mail to that server stays in the queue. Only one server is the problem, hundreds of other mails gets through.
In the log I can see the message:
2013-07-17T00:07:28.772Z,SMTP_Send,08D03766DE41AC86,0,,x.x.x.x:25,*,,attempting to connect
I have noted that if a server really isn't reachable there are two lines in the log:
2013-07-17T00:02:26.805Z,SMTP_Send,08D03766DE41AC6D,0,,y.y.y.y:25,*,,attempting to connect
2013-07-17T00:02:47.852Z,SMTP_Send,08D03766DE41AC6D,1,,y.y.y.y:25,*,,"Failed to connect. Error Code: 10060, Error Message: Ein Verbindungsversuch ist fehlgeschlagen, da die Gegenstelle nach einer bestimmten Zeitspanne nicht richtig reagiert hat, oder die
hergestellte Verbindung war fehlerhaft, da der verbundene Host nicht reagiert hat y.y.y.y:25"
But I only get one line.
Telnet to Port 25 of the server works without a Problem, so it can't be a network or Firewall problem. I have started Wireshark: if the Exchange server tries to send a mail to the non working server, there are no packets captured. It seems Exchange does not even try to connect to the other server.
Does anyone have seen this before?
Best regards,
Manuel