we have a problem on our Exchange server 2007.
I have currently 300 undelivered emails to various addresses. I'm getting this error message
421 4.4.2 Connection dropped
I checked the size of attachments and the messages aren't too big (20 KB to 6000 KB). From 200 mails to various emails addresses 137 weren't delivered.
We don't have any problems with incoming emails, but 20% of outgoing emails just sit in a queue.
Is this a DNS issue ?