[Dovecot] process_limit must be 1

Hello,

recently I have migrated a dovecot configuration from a Red Hat 5 to a CentOS 6. Since the versions of dovecot are quite the same (dovecot-2.0.1-1_118.el5 vs dovecot-2.0.9-5.el6.x86_64), I was thinking that copying the configurations file from one server to the other was a good thing, but instead, when I try to start the service, I have this bad error:

Avvio di Dovecot Imap: doveconf: Fatal: Error in configuration file /etc/dovecot/dovecot.conf: service(anvil): process_limit must be 1

Does anyone know why I am getting this? Is there a change in configurations between the 2 versions, is it a known issue or I have to check something else?

thanks in advance

Fabio Ferrari