MAX CLIENT THREADS

TCP/IP-channel-specific options: MAX_CLIENT_THREADS (integer)
This SMTP/LMTP client option takes an integer number indicating the maximum number of simultaneous, outbound connections that the client  channel program will allow. Note that multiple processes may be used for outbound connections, depending on how you have  channel processing pools  set up. This TCP/IP-channel-specific option controls the number of threads per process. The default value is 10.

See also:
 * job_pool
 * TCPIP-channel-specific options