By mail or in mail

I think there might be a small typo there!

If you meant to ask "by mail or in mail", I'd be happy to help clarify.

"By mail" typically refers to sending something through the postal service, such as a letter or package.

"In mail" is not a common phrase, but I'm assuming you might mean "in the mail", which refers to something that is being delivered or received through the postal service.

So, to answer your question, if you're asking whether something should be sent "by mail" or "in mail", I'd say "by mail" is the more common and correct phrase.