I use SPF records for one of my domains and it has significantly reduced the amount of spam I receive, especially "back scatter" spam (http://www.spamhaus.org/faq/answers.lasso?section=ISP%20Spam%20Issues#109).

There is a SPF wizard here http://spf.pobox.com/


Josh
-- 
http://josh.id.au/

On Mon, Oct 17, 2005 at 07:34:46AM -0700, Bill Mitchell wrote:
> Does anyone use SPF records? I've never really been
> able to work them out.
> 
> Currently I've got an Australian spammer using my
> domain as a return address its a major pain. 
> 
> Bill