When ending an email, should I use "Yours faithfully" or "Best regards"?

I've been taught to end business letters with "Yours faithfully" but I can see from my daily correspondence that "Best regards" is more commonly used but seems more informal.

What term should be used and under what circumstances when writing email these days?

NOTE: If other terms exist too (for colloquial use or extreme formalism) I'd like to know that too.

Solution 1:

When working in England, I've found that "Regards" is most common, even amongst parties that have a good relationship.

When working in Australia, "Best regards" is much more commonly used. Using simply "Regards" would seem quite standoffish.

I'm not sure which is most applicable in Denmark.

Solution 2:

The traditional British style would be to use yours faithfully for letters starting Dear Sir, Dear Madam, or something grander such as My Lord, and to use yours sincerely for the slightly less formal letters starting with a name such as Dear Mr Smith, Dear Baroness Jones, Dear Sir James etc.

The point of both is say that the writer has been telling the truth. There are some minor religious connotations in yours faithfully so for example Rothschild's investment bank will often sign yours very truly. There was an old-fashioned ending along the lines of I have the honour, Sir, to remain your obedient servant sometimes shortened to I have the honour etc. but that is now rarely seen.

Best regards is clearly informal, and should be used for informal contexts. Examples might include email or letters starting Dear Jane