[Mailman-Developers] regexp in Privacy Options - (?!...) ?

[Pavel Petrovic]

hi,

i'd like to use the following regexp in the 
"hold posts with header value matching a specified regexp." 
option of the privacy options section of mailman 2.0.10
list owner config pages:

from: (?!john).*@hotmail.com

to make all messages coming from hotmail require admin approval,
except of messages coming from john at hotmail.com, which should
be accepted without approval.

i cannot make this work, though.
any hints how one could achieve this functionality?
(more specific: the list should be open for posts from anywhere
without approval, but hotmail and similar spammers should
be filtered, except of some known exceptions)

thanks,
pavel.

p.s. please reply also to my address as i am not member of this list.