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.
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.
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
I was always taught to use 'Yours faithfully' in letters when addressing someone I didn't know, and 'yours sincerely' for people I did.
However no such rules exist for emails, and using either of these valedictions would seem quite stuffy and overly formal. I'd use them only (if you wished to use them at all) in formal, written correspondence.
'Best regards' is a fairly standard valediction that is neither too formal or too informal and would be suitable for any business email.
Tragicomic's comment on your question gives you a number of suitable alternatives.
The formal rule, at least in Britain, is that if you're writing a letter to a person whose name you don't know, you start with "Dear Sir or Madam", and you end with "Yours faithfully".
If you do know the name, you start with "Dear Mr X", and end with "Yours sincerely".
However, as you note, "Best [or kind] regards" is much more common these days. But again it would only be used when you know the person's name - and I would probably say, only when you actually know the person themselves.
I'm surprised no one's mentioned Yours truly. It strikes me as a shade less officious than yours faithfully but not as boilerplate as Best regards or its weird sister, Best.
Yours faithfully, used to end a letter, is chiefly British and it used in a formal letter to someone whose name you do not know. Best regards can be generally used, and it would be my preference.
There is a trend that I approve to stop using those complimentary openings and closes. They are relics and literally are usually ridiculous:
Dear Sir: Your employment will be terminated on 31 March 2011. Yours faithfully.
What I see increasingly in e-mail correspondence is 'BR'. It seems to me that this, along with the strange and pointless-seeming 'best regards' itself, is essentially business-speak and meant to make the correspondence, and by extension the writer, seem 'professional'. I can't bring myself to use it myself, so in such correspondence I tend to sign myself
best
Christopher
But I doubt it will catch on.
Despite the name, emails are not letters. Many people try to equate the two, but they are completely different mediums, and different rules have historically applied.
In former times many people had very limited bandwidth and email storage capacity, and would in fact get annoyed (if not downright hostile) with people who put large amounts of unnessecary information in an email. This includes salutations (which are redundant with the email's automatically attached header), and excessive or unnessecary signature/footer information. Return contact information used to be common in footers, just in case it got somehow mangled in the email header. However, it has always been considered common etiquette (aka: "netiquette") to keep footers to 4 lines or less. A lot of this has been formalized in RFC 1855 (section 2.1.1 is for email).
These days those issues are by-and-large moot. However, getting right to the point, and quitting when you are done, are still considered better form that adding a whole lot of polite chuff around the meat of your conversation.
For further detail, you may consider picking up a copy of The Elements of E-Mail Style, although it is about 20 years old, so it may be a bit dated.
