Now that I've been through a couple interviews and have been accepted to a school, it's much easier to get a letter of rejection and have it not affect me so much on an emotional level. It's in no way easy, as it always feels somewhat like a slap in the face. No matter how kindly they word their rejection, it's still a rejection. Granted, not all schools try to be nice about it. One school just put it blatantly, saying something along the lines of, "After our review of your application and qualifications, we have determined that you are not a competitive applicant."
However, sometimes when schools try to be nice, it just gets confusing. For example, when they try to explain it away by saying that "this year's was an exceptionally competitive applicant pool" or that "our standard minimum requirements for an interview include a 3.0 science GPA and 27 MCAT score, as well as volunteer/community involvement and clinical experience." I don't like sharing my statistics, but I will say that my numbers are significantly higher than both of those minima, I have something like 2200+ hours of volunteer experience over the past nine years, 2.5 years of nuclear physics research experience with multiple publications, and more than 200 other hours of clinical volunteer and shadowing experience in a hospital emergency department environment. I've served as a tutor and teacher in a wide variety of environments, been on multiple international missions trips, and worked with dozens of different cultural groups in my career in human resources while going back to school for the premed course requirements.
So when I get generic explanations that tell me I'm not a competitive applicant or didn't meet their standards, I start to wonder. Did they mix up my file with someone else's? Did they read my file at all? Usually, I tend toward disbelief and end up chalking things up to a difference in fit or perception that resulted in them sending me a generic rejection letter. Maybe my reviewer didn't like an essay, or maybe they had so many qualified applicants that the decision-making process for awarding interviews turned into a large-scale game of darts. I can just picture it now - in a huge gymnasium with each applicant's file stuck to the wall, the Dean of Admissions grabs twenty-five darts and lets them fly; whoever's application ends up getting a dart gets an invitation to interview. Who knows?
Regardless, when I receive rejections, I do my best to not take it personally. That's my best advice to others who might be reading this as they prepare for the application process, or perhaps are going through it with me. Try not to take things personally. It does no one any good, least of all you. You will most likely get rejected by way more schools than you initially anticipate. It's very possible that schools which you considered to be shoe-ins will be some of the first to reject you. That definitely happened to me; some of the schools which I statistically (based on average MCAT scores and GPA) considered "backup schools" didn't even request a secondary application! The most important thing is to keep your head up and remain confident, anticipating that perfect-fit school and the career to which it will lead you.