No Free Slaves Error
If you have not already, you should install PGBouncer as per Appendix G in the Administration Guide. This can greatly increase database performance.
You can increase the maximum number of MimeDefang processes as follows.
First: Ensure that you have enough free memory using the 'free' command.
Each MimeDefang process can take around 20-25MB of memory or more depending on how many lock slots are made available.
In the file /etc/postgresql/X.X/main/postgresql.conf (the X.X will be your PostgreSQL version number), there is a line for
the default of which is 100. This represents the total number or connections allowed to PostgreSQL, given by the sum of all MIMEDefang slaves from all cluster members PLUS the number of expected simultaneous human connections. Thus, once you increase the max_connections, you will also need to increase the per-member connection limit by no more than ((new limit)-(old limit))/(number of nodes) using:
in the [mimedefang] section) of the /etc/mail/canit/canit.conf file.