[Dovecot] lmtp (xxx@mydomain.yy): Error: user xxx@mydomain.yy: Initialization failed: Namespace '': mbox: mbox requires client_limit=1 for service

new Dovecot 2.0.8 installation on Opensuse 11.3 I got the error "lmtp (xxx@mydomain.yy): Error: user xxx@mydomain.yy: Initialization failed: Namespace '': mbox: mbox requires client_limit=1 for service" while trying to transfer mails by lmtp from postfix to dovecot. I googled and looked on the dovecot wiki about this client_limit issue, but no success. What's the syntax of the client_limit and where to place it? Into which config file? Inside the global namespace doesn't seems to work (error on dovecot start). -What's the side effect of this setting to my IMAP clients? Are multiple imap connections to the same mailbox still possible?

Regards Birte Nauer