I have a situation that just started in the last day or so. One of our users regularly sends an email to a group (about 20 - 25 names) at a specific destination domain. Yesterday the mail was got held in the mail.box with the message that the destination server was not responding. Went into mail.box and flagged the held messages and released them. Waited for some time and there was no action. Shut down the Domino server and restarted it. During start-up it sent the offending emails. Tried sending an email to a single person at that domain and it got held as well. The domain that we are trying to reach is a major school district and the I can ping the mail server without trouble.
You will need to review the conversation which your Domino Server is having with the destination-host for more information on why this is happening. Since this is occurring with only one Domain, you may want to wait until “off-hours” to do this - or else it will be difficult to determine what output in the Domino Console corresponds with the problem.
Execute the following Domino Console commands to enable SMTP debug which will yield information regarding the conversation your Domino Server’s Router Task is having with the destination host:
set config smtpclientdebug=1
restart task smtp
restart task router
Once the debug is enabled, you will see a significant amount of information regarding the SMTP-conversation your Domino Server is having with the destination-host. These messages will be prefixed with the string “SMTPClient:” in the Console. At tjhis point, send a test-message to the problematic Domain & then monitor the SMTPClient output in the Domino Console.
Look for messages like the following:
[055C:0009-05F8] SMTPClient: Data Send Failed 16376 bytes, Status: 2562
[055C:0009-05F8] SMTPClient: Connection broken after an error sending DATA command