Bottom line: what’s done is done.

I wouldn’t waste too much time stressing over this one. An application or a vita is one thing. A thank you note is something else entirely. Hopefully, the reader is not going to spend a lot of time over analyzing a routine thank you note. In fact, it may not even be read very thoroughly at all.

Best of luck to you in your future educational endeavors,

~M~

I think it will depend entirely on the person reading it. Not that it necessarily matters for this answer, but I have an MBA and have interviewed countless amounts of people for jobs at my company. (I have not interviewed anyone to get into the school, however.) I am kind of a stickler for grammar and spellng, so if there errors in a thank you letter it does change my opinion of the sender. However, I have a boss who still doesn’t know the difference between their and they’re, so something like him would not notice your letter at all. I wish I could say something more helpful! Perhaps the person reading it will just skim it. Incidentally, while I do appreciate thank you notes, I once had a candidate hand-deliver a thank you note to me at the end of the day he had interviewed. I thought that was kind of creepy!

Almost none, your letter will likely not be read with any degree of attention. At best it will be noted that you sent a thank you letter not the content of the letter.