Mail ISPConfig 3 server suddenly stops working with ISPConfig 3 master
I'm sorry about that but I really need some help.
I have got and ISPConfig3 installation with 2 servers. 1 master which controls everything but mail and a second one, debian lenny vps, which deals with mail and nothing else.
Everything was running ok, but suddenly que have got into trouble because every change we make about mail just piles up in master queue forever.
I have followed every suggestions I have found in forums with no success. Master server.php shows no errors. Slave (mail) server.php shows "finished" even though I have tried to switch debug on manually (I can't do it trought ispconfig interface because the slave seems to have stopped reading changes from master).
I haven't updated or changed any OS either. It just happened from one day to another. The secondary mail server is running properly but we can't change anything in it because of this broken link with master.
Is there any action that I could take in order to try to find what is going on here?.