tl;dr: Is it okay to FedEx the followup thank you note?
I'm sitting in the airport, waiting for a flight back home across the country having just finished my first management interview. I've been with FedEx Express for four years and am working on moving into management. I prepared to an okay level (far from perfect, d'oh), my questions floored them in a good way, and I think they reacted well to my close. Of course, I also have no idea for sure, but whatever.
I was told they should make their decisions in 2 to 3 days. With my layover in Chicago, it's going to be a long trip back to Washington State, leaving it as 1 to 2 days. I wouldn't dream of e-mailing the thank you, but with cross country snail mail, it's almost certainly going to take too long. I probably should have had everything prepared to drop it off after I left the motel, but alas, I didn't.
It's the note and not the delivery mechanism that makes the difference. FedEx will be fine
If you work for Fedex
Sending the thank-you via Fedex is appropriate in every way. To me, sending it via a competing service (USPS) would be a bit strange.
Sending a thank-you ranks you above 90% of your competition. Send it and Good luck!