Formal emails

Hello!
I work in a Multi-national company. So obviously it has corporate culture. I want to ask that while writing formal mail to boss or some senior person, at the end of mail can I close the mail by Thanks, like:
Thanks,
Prachi
or should I always use "Regards".
Please advise,
Thanks,
Prachi

[Anglika]

Use whatever is polite. Best wishes is another ending much used.

[Ouisch]

If you are writing someone senior to you, it's better to sign it "Thank you," instead of "Thanks."

"Regards" is fine, too, but if you're requesting information or expecting a reply of some sort, I think "Thank you" is more appropriate.

[mykwyner]

You will never go wrong with "Sincerely."