After an interview did you get regret letter from employer? What happened about you?

Yes, I went to an interview then got scheduled to meet the CEO, and then all of a sudden they decide to promote from within and told me that they will keep me in mind as soon there is a vacancy... 

Usually regret emails are sent to me after applying to a job that I am not selected. As for the interview, I do not remember I got regret letter may because the closing sentence which is said at the end of the interview "We will call you if your selected to work with us".

Regardless of the outcome of the interview is important to try and work is required of you during the interview, but some people are curious to know the reason for the rejection or weakness to reject the same person point

I did not get regret letter after an interview because I did not go to an interview which is not relevant to my qualification and skills!