Well I looked around and I know we have had this happen during moves and new servers before...but I couldn't find it. I moved my server to a new machine, and somehow it is not sending emails out.
Do you have full access to the new server? If so, then first thing to do is check the mail logs / mail queue and see if it's attempting to send anything out.
I have full access to the machine as it is sitting right next to me... (actually all 10 of them are right here :/ loud buggers.. anyway I will check in the morning. I didn't see anything earlier when I was looking through the logs but I was not focused either.