What is a more commonly used term for Deferred Messages?

The term "Deferred Messages" refers specifically to messages that have been temporarily rejected or postponed by a mail server with the intention of accepting them at a later time. This process is often a part of spam filtering or to manage server load efficiently. Greylisting is a widely known technique used in email systems to temporarily deny acceptance of email from unknown senders, requiring the sending server to retry sending the message after a certain period. This approach helps in reducing spam since many spam servers do not attempt to resend messages.

In contrast, the other terms provided do not accurately describe the nature of deferred messages. Blocked Messages typically refer to those that are outright rejected based on specific criteria, rather than deferred. Permanently Deleted Messages are those that have been removed and will not be retried or reinstated, while Suspended Messages imply a temporary halt rather than the deferring of a message for future retry. Hence, the term that aligns most closely with the concept of deferred messages is greylisted messages.