How do I know IP of an email?

You should ask this question in a different forum

This site is organized in forums. Your question should pertain to the forum you post in. There is an e-mail forum and I've requesterd this thread be moved to it.

You need to view the header info for the e-mail. How you do that depends on the e-mail client you use.

Simple answer is look at the header information.
Problem is it isn't that simple as this will only track back to the mail server, plus IP's can be easily spoofed.