I am in the middle of a migration where I am using dual delivery. Email comes into my existing exchange server and then I created forwarding rules to for each user that has been migrated to the new google apps domain. I have two sets of MX records. One points to mydomain.com and the other points to apps.mydomain.com. Mail flows and the MX records work, but it seems like mail stays in the exchange outbound queue until about 20 emails fill the queue and then it sends. This only happens for my apps.mydomain.com bound email. All other emails flows immediately (i.e. gmail, hotmail, etc.). I realize this could be an exchange issue but I've tried everything to no avail.