Electronic mail that is not spam (junk mail); legitimate e-mail.(noun)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "nonspam" in a sentence
"The spams are scoring higher and the nonspam is scoring even lower."
"Windows Mail is a mild reworking of Outlook Express whose big new feature is a spam filter that in my tests flagged nonspam as spam and vice versa an unacceptable 10% of the time."
"Arguably, these are neither my spam nor my nonspam mail."