1. greylist - Noun
2. greylist - Verb
(law) A list, resembling a blacklist, for less serious offences.
(Internet) A technique for blocking spam (junk e-mail) by temporarily rejecting mail from unknown senders. A legitimate sender is likely to try sending again after a delay.
greylist (third-person singular simple present greylists, present participle greylisting, simple past and past participle greylisted)
(transitive) To place on a greylist.