What are the normal forms of valediction (signing off letters and emails) in Chinese? For example, how do they normally sign off letters?  We normally use 'Yours Faithfully' or 'Your Sincerely' but we might not be so formal in emails and instead just 'Regards'.

What is standard practise in Chinese for both letters/emails?
謹上 or 敬上 is fairly common. Your own name precede this closing term, contrary to English.