Got one solution but not the ideal one yet:
In the listname.config file for the majordomo list there is a parameter "maxlength" which limits the size of the messages in the list.
# maxlength [integer] (40000) <resend,digest>
# The maximum size of an unapproved message in characters. When
# used with digest, a new digest will be automatically generated if
# the size of the digest exceeds this number of characters.
maxlength = 400000
O I suggest taking the relevant entries out of /etc/aliases and putting them
> in a single user's .procmailrc file instead (I've done this, works fine).
> Then you can pre-sanitize messages using a simple procmail rule as described
> in the sanitizer's manual.
> Simply killing all attachments is relatively simple once you've got the
> Sanitizer up and running.