Can't change min-bounce

Here's a strange one. I want to change the default setting for the number of bounces before a user is automatically removed from 4 to 2. I've gone into rc.custom and set: #minbounce = 2 # no. of bounces before removal However, it still won't remove users unless bounces exceed 4, as the below verifies: Subject: Returned mail: see transcript for details Auto-Submitted: auto-generated (failure) X-Diagnostic: Mail to yyyyy@xxx.com bounced 3 times X-Diagnostic: Mail coming from a daemon, ignored X-Diagnostic: Possible loopback problem X-Envelope-To: routing-request Any thoughts? Thanks in advance, Irwin