I've been using mailhop.outbound.org, DynDNS's mail relay service for Outbound mail through Exchange. I've got two domains that I send mail from through Exchange. Lately my outbound traffice to companies like generac.com and adobe.com can sit in my queue and are not relayed through the mail relay service. My clients get messages back that say:
joe(not his real name)@adobe.com on 4/10/2010 11:01 AM
Could not deliver the message in the time limit specified. Please retry or contact your administrator.
Dyndns tells me that they're not having any trouble with the mailhop.outbound.org service.
I'm looking to try to indentify the problem and resolve the issue.