Rejection hurts. Academics thrive on earning the respect of their peers and it's tough to think that someone doesn't want you. So go ahead and be depressed for a day or two and then move on.
Stanford is my ultimate rejecter, having turned me down for undergrad, grad, junior and senior faculty positions without the least bit of interest. But I got my revenge–I once got a parking ticket at Stanford and I never paid it. Ha!
A few people have complained to me about how rejections letters are written. A rejection letter contains exactly one bit of useful information. The rest is irrelevant and you should not let it get to you.
Suppose Alice sends email to her friend Bob asking if Bob's department would be interested in her. In academics, Bob usually won't give his real thoughts ("We are looking for strong candidates and you are not one of them"), instead he'll find some property P such that Alice has P but they won't hire in P, for example "Unfortunately we are not looking for any cryptographers this year." A couple of warnings for Bob:
- Be sure P is not illegal, i.e., based on religion, race, gender, etc. Even if you don't discriminate, saying that you do is not a smart thing.
- Bob's department might end up hiring a cryptographer. Then Alice will realize that Bob didn't want Alice because she was a cryptographer, rather he just didn't want Alice.