[Dovecot] Max number of mail processes

Dovecot version 1.1.11. Error: Maximum number of mail processes exceeded (see max_mail_processes setting).

I can't seem to get rid of these errors. I get batches of these errors about 4 or 5 times a day. I have a cron-job checking for the existence of this error and then I reboot dovecot when I see this error, but what is causing this error ? What I am reading on the Internet about this particular issue has not helped to resolve the issue. I would really like to know how many mail processes it thinks that it is using at any one instant in time. Is this possible ? Maybe then I can track the reason for the error.