As of Mailman 2.1.21 the method for checking accept_these_nonmembers has changed again.
For Mailman prior to 2.1.10, use the SpamAssassin.py attached to comment #18.
For Mailman >= 2.1.10 and < 2.1.21 use that SpamAssassin.py patched with the patch attached to comment #22.
For Mailman >= 2.1.21 use the SpamAssassin.py attached here.
As of Mailman 2.1.21 the method for checking accept_ these_nonmember s has changed again.
For Mailman prior to 2.1.10, use the SpamAssassin.py attached to comment #18.
For Mailman >= 2.1.10 and < 2.1.21 use that SpamAssassin.py patched with the patch attached to comment #22.
For Mailman >= 2.1.21 use the SpamAssassin.py attached here.