Everybody knows that you’ve got to send a thank you note after your interview, and yet I continue to be surprised by how many people don’t. They really do make you stand out from the crowd, and they give you another opportunity to point out a key item or two in your favor…it should always be substantial. It should mention that you enjoyed talking with them, some additional thoughts about how you and your skills are a great fit, and what you learned that makes you even more enthusiastic about working there. But do them quickly. Timing matters.
E-mail thank you notes are entirely appropriate. Handwritten thank yous are of the past. They work only if you can get them out on the exact same day, because speed is a strength here. Still, you should send an e-mail one because there are hiring decisions that happen while the post office still has your letter.
(Didn’t get the address? Google the interviewer: *@thecompanyname.com. It should lead you to the email address of everyone who works there.)