For those who have domains hosted on Brinkster and are looking to add SPF/SIDF to help stop SPAM, I recommend using the following:

   v=spf1 mx/20 ~all

Notes:  Just putting mx isn't enough, as Brinkster does not send their outgoing mail on the same servers that they accept incomming mail.  So the mx/20 gives the least maintanence way of saying anything with an IP belonging to Brinkster near their incomming MX servers.  You could also lookup the IP's of Brinksters outgoing mail servers, but then whenever Brinkster changed them your record would be invalid.  It would be real nice if Brinkster setup their own SPF records for their domain (at which point you could do a include:brinkster.com)--but they have not done that..yet.