J C Lawrence explained:
Translation: only one-off single-addressee messages are cost effective.
Bulk mail of any form, be it spam, mailing lists or other mass
broadcasts are penalised.
like I said, I really should have an FAQ :-)
you are right that any bulk mail to strangers[1] is penalized either by paying 
the postage or trying to navigate the filter hazards.  However, as I have said 
one million times in teh past and I will say million times in the future 
"strangers cost, friends fly free".
In the short-term mailing lists will be defined as friends through manual white 
list.  White listing mailing lists is hazardous and creates a hole for 
spammers[2].  in the longer-term with white list by public key, mailing lists 
will only need to sign a message once and then they can deliver to the 
subscriber list without penalty.
[1] a stranger is defined as someone you have not e-mailed in the past.  This 
will evolved to someone you have not accepted their public key yet when the 
camram infrastructure is in place.
[2] white listing the mailing list creates spammer holes because they can just 
put the mailing list address in CC and they get by simple white listing by name 
filters extremely easily.  Personally, I want to filter most of my mailing lists 
because they are gateways for spammers such as the freeswan and openSSL mailing 
lists.
I hope that clarifies its sufficiently.  If not, feel free to e-mail me and I'll 
try to do better.
---eric
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