I was recently asked by a client about the best way to send post-interview thank you notes - email versus snail mail. This client said he had read conflicting advice online.
As a former Harvard admissions decision-maker who used to receive thank you notes, I can tell you that I strongly advise sending your thank you notes by good old USPS. The reasons are twofold:
1) Email may be viewed as lazy. Hand-written thank you notes take more time, which shows.
2) To put an email thank you note in your file, the receiver needs to take the time to print out your email. You don’t want any barriers between you and your good impression.
I do recommend getting those handwritten thank you notes in quickly. The night after you’ve completed your interview or the next day is a good time to write and send.