I got my email for the $25 code. I followed the link to the SW web site about exclusions. This is what it says.
$12.50 each way ($25 roundtrip) discount valid for one-time use at southwest.com off the total amount of any roundtrip purchase before taxes and fees.
Purchase must be made between April 1, 2010 and August 1, 2010 for travel June 1, 2010 through December 1, 2010.
Blackout dates apply July 1, 2010 through July 5, 2010, September 2, 2010 through September 7, 2010, and November 22, 2010 through November 29, 2010. If any portion of travel falls on a blackout date, the discount will not apply.
The discount is only valid with the provided Promotion Code and is not combinable with other Promotion Codes or fares available exclusively through the web tool DING!.
This promotion includes only Wanna Get Away Fares.
Roundtrip purchase required.
Changes made to the itinerary after purchase may eliminate qualifications for this promotion.
Youth, Child, Infant, and Military Fares are not available for purchase at southwest.com.