This can be done with a custom handler. See for an example to be put in Mailman/Handlers/, and see for a file that can be edited and put in lists/LISTNAME/ to set parameters and enable this for the LISTNAME list.

See 4.67 How do I implement a custom handler in Mailman, e.g. to mung headers or filter posts based on regex searches of the message body? for more info on custom handlers.

MailmanWiki: DOC/4.91 Can I limit the number of posts in a given time period per member and/or per list? (last edited 2015-02-01 16:37:27 by msapiro)