Thanks for the reply.
sometime user setup some filter to forward / auto bcc to other mailbox / user, maybe the receiver also have some filter do the similar thing. then it loop the mail and send out 1800+ mail within 1 hour. it jammed the active queue so we need to remove the jammed no use 1800+ email from the queue.
I found that the active queue send out very slow, 5 mins around send out 20+ mails. we need 10+ hours to send out all 1800+ mail last time. so want to have a queue management for it. or any setting / suggestion I can config the postfix?
Thanks!