Writeability

Business Correspondence: If you start a letter with "Dear Mr/Ms/Mrs/Miss/Dr X", end "Yours sincerely" or  "Sincerely yours".

If you know your reader quite well, you can start "Dear + first name" and end with "Best wishes" or "Best / Kind regards" or "Regards".

If you don't know the name of the person you are writing to and start "Dear Sir or Madam", end with "Yours faithfully".

You can also start and end emails in the same way as letters. If you are writing to more than one person, you can omit the salutation completely and start with your objective. Other ways you can end emails is by writing "Thanks" or even "Cheers", but never "Bye".