How to sign an email

There are formal and informal emails.

Formal letter writing once had a long set of rules about what was appropriate and these rules were generally followed. Start "Dear Sir or Madam" and end "Yours faithfully"; start "Mr Smith" and end "Yours sincerely". After that you added your signature, full name or initial plus surname as appropriate. For a job application or proper formal request this is probably still the best format, even if you have been asked to apply by email rather than letter.

However emails are more flexible and new conventions apply.

You might still use "sincerely" (as opposed to "yours sincerely") in a formal email which would be accepted for a letter of formal intent.

Slightly less formal would be "yours truly" or "regards" (or "best regards" or "kind regards").

More generally a simple "thanks" can be used in many circumstances. "Much appreciated" would be an alternative."Yours aye" is used in Scotland, especially between friends.

Informally a wider range of terms is available: "be seeing you", "see you soon", "all the best", even "best" (which I don't like).

My personal favourite is "Best wishes" which to my mind works in both formal and informal situations.

Between friends icons ;-) or :-) or jokey phrases echoing what would be spoken in person are all accepted, but remember that formality and respect go together, while too much informality can be taken amiss by one's future parents in law or work superiors.