Postfix Service Stopped but Still shown in Processes List

I've stopped postfix services using CWP Interface. Infact stopped all mail services.
As soon as I restart the server the load is <1 and processes running are <200 but with the time number of proceeses by user 'postfix' start running and server load starts increasing. Withing an hour load goes beyond 400 and it makes the server inaccessible.
I have been facing this for 2 days now and restart only fixes the problem for few minutes.
Can anybody suggest what is the problem and how it can be fixed?
Waiting for a positive response from community.