Header Filter Rules
The header_filter_rules set a list of filters for Mailman to check. Those matching will be Held, Rejected, Discarded, or Accepted as set for the rule. Defer turns off a filter rule until you again select either Hold, Reject, Discard, or Accept. For additional assistance with this, please contact email@example.com.
Bounce Matching Headers
The bounce_matching_headers allows you to set specific regular expressions that Mailman will search for in message headers an then hold that message for moderation. For example, the 'from: .*@uplinkpro.com' line in the image instructs Mailman to hold any message from any email address that ends in @uplinkpro.com.