Greylist

[Japtastic]

What happens to these messages? Do they get deleted/rejected or are they sitting somewhere on the server?

 

[HenryAZ]

What happens to these messages? Do they get deleted/rejected or are they sitting somewhere on the server?

Not sure from which perspective you are looking at this (sending or receiving server).

Greylisting is done by the receiving server, by temporarily rejecting a message with a "soft bounce" (4xx reply code). It is then entirely up to the sending server to retry delivery at a later time. If the message still exists, it is in the sending server's queue. Whether or not it still exists depends on the configuration of the sending server.