When Regards Is Used?

Using regards in an email closing suggests that you have respect for the recipient, but not necessarily a close relationship with them. Because it is less formal than sincerely, expressions with regards are perfect in emails, which tend to be less formal than letters anyway.

Is it rude to say regards?

You should never use it when you don't legitimately have something for which to thank the recipient, or else it comes off as sarcastic and rude. That's not how you want to be seen in an email! When in doubt, go with a formal salutation. It's better to be seen as kind of more formal as opposed to rude.

Should I use regards or respectfully?

“Best regards” typically suggests that you respect the recipient, but don't necessarily have a close personal relationship with them. Other similar closings include “best wishes,” “all the best” and “warmly.” More formal closings are “sincerely” or “respectfully.”