It has been running fine for two years. Two days ago messages started getting stuck in the queue, I am on FIOS so I am using smtp.frontier.com as a smarthost. I look at the queues and the messages are stuck in the smtp.frontier.com queue with the last error on the queue being "451 4.4.0 DNS Querey Failed".
I am going to say nothing has changed on the server but obviously something has. I have no idea where to start on this. I found an article that said to download and install Rolluo 3 for ES 2007 to correct the problem but that patch won't even install.