Message Size Limit
(optional) Defines the maximum size of messages that may be contributed to the mailing lists. Any contributed message over this size will be automatically rejected.
This setting is useful sometimes mailing list members will try to send a large attachment to a mailing list (such as a sound file), and most mailing list members do not want to receive this size of a
file from the mailing list. So, this feature will block excessively large messages from being sent.
List administrators are not restricted by this message size limit, their messages can be of any size.