Probles with A queues A5 A6 and A7

Hi,

I have 2 servers and looking in the Message Queuing I can see a backlog of messages in there.

Server 1

A5 = 4240

A6 = 10329

A7 = 419

Server 2

A5 = 1341

A6 = 6786

A7 = 202

I have done some basic things to see if they will go down, change the schedule, stop archiving for a bit, reboot etc. Nothing. It seems this lot is stuck in the queues.

My questions are this.

1) What are each queue used for?

2) How do I clear down each queue and would we lose data doing so?