What term is used as a synonym for Greylisting?

The term that serves as a synonym for Greylisting is "Deferred." Greylisting is a spam-fighting technique where the email server temporarily rejects an email from a sender it doesn't recognize. This rejection is not a permanent one; instead, it adds the sender's email address to a temporary holding list and requests that the sender's mail server try to resend the email after a certain period.

The main intention behind this method is to allow legitimate mail servers—those that follow standard email delivery protocols—to retry sending the email later, while many spam servers will not attempt to resend. Hence, the state of the message being temporarily held instead of permanently rejected is best described by the term "Deferred," indicating that the email will be processed again later rather than being immediately discarded.