"it depends"

. do you believe him?
. is he really subscribing and then posting?
. how active is you list esp. via new subscribers?

I've done some number of the following on lists that I operate with a
high-level of success (that not 100%), via list definition keywords:

* SUBSCRIBE= OPEN,CONFIRM
* SEND= PRIVATE
* DEFAULT-OPTIONS= REVIEW
* FILTER= *@*some_hi_level_domain

Issued LISTSERV(R) commands:

QUIET DEL listname Luserid@bad_node
QUIET SET listname NOREVIEW FOR good_guy/gak@good_node

emailed postmaster@bad_node or abuse@bad_node about Luserid's spam.

/Pete Weiss at Penn State