I have a Windows 2003 64bit server that is a SMTP relay server. It filters emails with GFI MailEsesentials and then relays them to Exchange 2010. It only uses IIS SMTP. Emails are stuck in it's queue. I look in my Exchange 2010 event logs and I don't see anything pertaining to back pressure. I see no errors or even warnings. So, I assume it's something to do with my SMTP relay server. Any ideas?