[Mailman-Users] SPF best practices?

[Dennis Carr]

After a rash of bounces that brought to my attention that my SPF
record was not properly published, I rewrote my SPF record a bit.  What
I'm looking for is some insight on best practices and a second set of
eyes, as my list hosts for addresses all over the internet. 

The record is such:

v=spf1 ip4:206.225.172.6 a:bast.chez-vrolet.net a:chez-vrolet.net
a:smtp.comcast.net ~all

This is published as a TXT record as per specification.

The a:smtp.comcast.net is necessary so I can send email remotely
through my ISP and clear out successfully. 

I'm a bit bothered by the '~all', however.  I really don't want to do
'-all' as I'm concerned that anybody who posts to the list would cause
anybody on Yahoo or the MSFT owned domains (hotmail, live, etc.) to
bounce again.  

Anybody have any suggestions on how to make this happen *correctly*, or
if there are any revisions I should make to my record?

-Dennis Carr