I can’t remember the last time I wrote or received a personal letter. I suspect that, sadly, I am not the only one.
Business letters, on the other hand, are still sent and received fairly often. Writers often worry over which ending to use with which greeting. Many of the more formal closings are simply no longer used – Your most obedient servant in particular.
If you begin the letter with Dear Mr Smith, Dear John Smith, or Dear John, then you should end with Yours sincerely. If you use the first name only and know the person well, you could use With kind regards, Best wishes, or a variant of these. The choice that you make should reflect the level of formality the letter requires.
If you begin the letter with Dear Madam, Dear Sir, or Dear Sir or Madam, you should end with Yours faithfully. Yours truly is a less formal alternative.