How to limit Zimbra SMTP outgoing threads?

[ErikRojas]

Hello. I would like to know if there is any way I can configure Zimbra MTA to limit outgoing smtp threads to an external host. By default Zimbra creates as many outgoing threads as needed according to the quantity of mails in the outgoing pool. But we have several users and extremely limited bandpass.
So I need to limit those threads to no more than 5 simultaneous SMTP connections in MTA retransmision to external host configuration.

Thanks for your attention.