I once had the opportunity to speak to Mr. Kraby and asked him this very question. He told me that generally speaking, Delta's minimum is 2.5. However, he suggested that if I'm in that situation, I could add an addendum to my application explaining the extenuating circumstances which may or may not have led to that level of academic performance.

Disclaimer: Delta has NOT called me for an interview!

But really, the impression I got is that they realize no one is perfect. If you own it, accept responsibility, and for bonus points tell them what you've learned and why you're now a better person, they'll at least give you a shot.