I have some BES user I want to migrate from a zimbra server to another

When I migrate a mailbox from server1 to server2 the BES stops forwarding email.
If I try to access an attachment from the BB the BES server correctly download from the mailbox on the new server.
If I check with netstat the bes has connection opened with all the servers.

When I reboot the server, it start again to forward messages and working properly.
Isn't there a way to close the open connection between the connector and the zimbra server for a specific mailbox so I don't have to reboot?

p.s. I got 10 Bold that are re-activated at each reboot
This time I tested reboot with the lan card disabled and mine has not reactivated. I'll let you know about others.

Ciao
AleX