Graham's spam filter

[Edward K. Ream]

I am an enthusiastic user of ChoiceMail,
http://www.digiportal.com/choicemail.html It has _completely_ eliminated all
spam to me, using a very clever trick.  Anyone wanting to contact me who is
not already on a "whitelist" gets sent a return email asking them to fill
out a short form at the ChoiceMail site.  Most spammers never even receive
this email because they use invalid return addresses.  If someone fills out
the form I get to approve it or reject it.  If no reply is received within a
specified time period, the sender is added to a blacklist. Anyone who gets
an email from me is automatically on the whitelist.  It's easy to add all
names in an address book to the whitelist, and it's easy to add an entire
domain to the white or black lists.  There are many other options, and that
is the gist of it.  It works great.

There is no way for spammers to circumvent ChoiceMail because ChoiceMail
never examines the contents of messages. The only drawback is that
first-time correspondents must fill out a very simple form.

We can all probably think of several reasons why this wouldn't work for
newsgroups.  I'd be more interested in hearing about ways some similar
scheme might work.

Edward
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Edward K. Ream   email:  edream at tds.net
Leo: Literate Editor with Outlines
Leo: http://personalpages.tds.net/~edream/front.html
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