Don,
Can you confirm with your friend whether the component that lack of coverage is MDA (mail delivery agent)? or protocols that mail clients use to access mail such as IMAP & POP3?
MDA's function is to deliver the message to the user's inbox (usually file directory) so that mail client can access the message through IMAP or POP3 protocol.
For the latter one, it is indeed lack of coverage in the quick guide. For the former one, many MTA covers the delivery. The quick guide didn't say much either, but it's a very different discussion than IMAP & POP3.