Check this out T-Mobile Launches GoSmart Prepaid Service Nationally on Phone Scoop

[rsk at gsp.org (Rich Kulawiec)]

On Wed, Feb 20, 2013 at 07:59:53AM -0500, Robert E. Seastrom wrote:
> If only there were some kind of method for Jay to publish which
> addresses are actually authorized to send mail on behalf of [snip]

SPF is snake-oil.  Here's something that works (salt to taste for
the MTA of your choice):

Connect:phonescoop.com	ERROR:5.7.1:"550 Mail refused, known forgery source"
From:phonescoop.com	ERROR:5.7.1:"550 Mail refused, known forgery source"

---rsk