filter unwanted domains?

[Chris Aitken]

I get a lot of spam.

Is there a way I can set a rule or set up a filter to send messages to 
senders that they need to email me again and have me accept them? Then I 
could add their domain to my friendly-domain list or somesuch. So, for 
instance, I could add ***@dsb1.edu.on.ca as friendly domain, or as I'm 
dealing with Sears now I could add sears.ca - that sort of thing...

Obviously I don't know what I'm talking about. However, I've received 
returns to my emails where an organisation has done this - then I email 
them again and they add me to some list so subsequnet emails will be 
accepted.

I don't what this is called - I don't even know what words to google to 
read up on this.

I'll pay a little (?) if I *must* but if there is something easy I can 
do in Thunderbird 1.0 then I'll do that.

Sincerely,

Chris
--
The Toronto Linux Users Group.      Meetings: http://gtalug.org/
TLUG requests: Linux topics, No HTML, wrap text below 80 columns
How to UNSUBSCRIBE: http://gtalug.org/wini/Mailing_lists