SENDER_HEADERS = ('from',) in mm_cfg.py should help with fake emails from spammers, see https://bugs.launchpad.net/mailman/+bug/1154004
Will only be a problem (relative to current config) in the unlikely event that user subscribed with address A writes to the list from address A in Sender (e.g. webmail; or SMTP-AUTH) but specifying address B in From (e.g. misconfigured SMTP client).
Version: unspecified
Severity: enhancement
See Also:
https://bugzilla.wikimedia.org/show_bug.cgi?id=46021