What usually happens to a message when server returns SMTP Error 550?

Question

What usually happens when a message recipient can not be found? Will it be deleted or archived on the (destination) server? In 550 case, will the message body be sent at all?

Action: failed
Status: 5.1.1
Diagnostic-Code: smtp;550 5.1.1 RESOLVER.ADR.RecipNotFound; not found 

In my particular case the recipient runs ESMTP Sendmail 8.12.8/8.12.8

Answer 1

This error is usually generated fairly early on in the SMTP conversation. Most servers will reject incoming messages for non-existent users typically before the sender has even transmitted the message body. This is done as an efficiency measure, and it helps prevent spammers eating bandwidth.

The recipient server, will likely log the rejection details somewhere (I don't know where sendmail might keep it), but it won't store the message itself, since it likely never arrived.