I have a strange issue that I solved by rebooting a couple times but it's back. I have an old E2K3 server that I'm pretty much just using as a relay because I have some developers who have the old server name in a ton of scripts and can't change it for now.
What I'm noticing is anything sending emails to that E2K3 server gets stuck in the E2K3 --> E2K10 Routing Group Connector queue. Whether it send the email seems to be hit or miss. Sometimes its delayed for several minutes to several hours. In fact I sent a test email at 8:30am this morning and it hasn't arrived. While i am tying this i decided to go ahead and reboot the E2K3 server and once i hit restart the email i sent at 8:30am came through. maybe it was a coincidence but im not sure.
I've deleted and recreated the RGC and restarted SMTP on E2K3 and Transport.exe on E2K10. I am not sure what changed in our environment. We don't touch the exchange servers other than to add and delete people.
One other thing of note, and I'm not sure if it's always been like this but it seems as though some of the emails from the developers servers send a mail from: <> which causes E2K10 to say Invalid system Resources, even though we have plenty of space.
The E2K3 server rebooted and some of the emails are being sent but i currently have 408 messages in the queue.