Should you write "bye", "regards" or "best wishes?"
More Email Quick Tips
The proper way to sign off is often not only the last, but also one of the most difficult parts of an email (almost as difficult as the greeting).
When in Doubt, End Emails with "Thanks"
When you can't decide what to write and have no idea what's appropriate,
- end your message with a simple "thanks" that is never out of place.

