so we have three gateway servers... all of them and the main server is running 14.x (whatever the last release was).
What I have noticed, and this could have been going on for quite sometime..... is:
Emails are received by gatewaw1 .. at 01pm.
They set in the spool, awaiting delivery to the main server, due to greylisting for up to 40 minutes.
Our greylisting is set to 180 seconds.
Why does this behavior occur ??