This just started on the 3rd of November. 2 Domains we have been sending email to back and forth with no problems all of a sudden are not getting there.
Users get the following error message:
"Could not deliver the message in the time limit specified. Please retry or contact your administrator."
I have checked our reverse dns and it is ok. We are not blacklisted from what I can see and we are not an open-relay. The emails just stay in the queue. I have forced the connection and that seems to work but shortly turns out not to have worked.
We are using ISA 2004 on the SBS Server with an internal and external interface on the SBS Server. As an attempt to fix this I changed the Ip address on the SMTP Virtual Server from All Unassigned to the internal IP of the server thinking that may help. It has not. A shot in the dark I know. It is back to All Unassigned.
I'm not sure where to go at this point other than to contact the other domains and see if they are stealth blocking us.