Both United and American are currently running frequent flyer mile giveaway sweepstakes. I can't share the links because they're personalized but you should be able to find them on Google or the respective sites. The only reason I'm mentioning is because they can be entered without a purchase, if you dig through the rules you'll find a way to enter using the old fashioned US mail method.
Posted by
Seattle, WA, USA ☔️
6790 posts
The United link can be found here:
United's Getaway Giveaway
The American Airlines link can be found here (at least I think that's the sweepstakes phred's referring to):
American Airlines "Dream big. Win Big Sweepstakes"
Both of these appear to be connected to the airlines' "shopping portals". The United one just requires signing in with your United frequent flyer account credentials. The American Airlines one requires you to join their "AAdvantage eShopping" program (presumably in addition to their frequent flyer program). I'm sure both are legit, the American Airlines one will likely result in some advertising email (aka spam), and you can probably opt-out of that.
Posted by
Last Frontier aka Alaska 🏔️
3561 posts
Yes, David is correct, Alaska airlines also running this sweepstakes, but you have to opt into the shopping thingy. No thanks!