==== Required information ====
- iRedMail version: 0.8.5
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):
- Linux/BSD distribution name and version: CentOS 6.0
- Related log if you're reporting an issue:
====
iReAdmin-Pro v1.7.0 (MySQL)
 
Hi, hope that is enough configuration information.
 
Today I had a large email server have a very slow problem. one user sent 
31,206 emails. I can't figure out how that happened and could not track   
it.
 
The result after I cleaned it out was that outgoing email was VERY slow   
taking 20 to 30 minutes to send email. The queue was loaded up with 7000 
items, after remove the bad users emails it was down to 4000
 
I have it down to 600 and out of frustaration I put all the messages in   
the queue on hold, this allowed me to release them one at a time, postfix flush, and it would deliver.

If I unheld 20 of them, it would take 5 or more minutes for them to deliver.

What do I do next?

There is no global throttling on.