e-mail vs netmail

e-mail is a noun but netmail is not a noun.

Word	Noun	Adjective	Verb	Adverb
e-mail	Yes	No	Yes	No
netmail	No	No	Yes	No

As verbs, e-mail and netmail are synonyms defined as:

Other synonyms of e-mail include email.

e-mail (noun)	netmail (noun)
(computer science) a system of world-wide electronic communication in which a computer user can compose a message at one terminal that can be regenerated at the recipient's terminal when the recipient logs in

e-mail (verb)	netmail (verb)
communicate electronically on the computer	communicate electronically on the computer