It's not exactly PGP's security model, but: - if you use SMTP-via-TLS and (IMAP/POP/MAPI)-via-TLS, attackers really can't intercept your mail - unauthenticated encryption still protects your mail spool at rest.

Of course, attackers gaining access to your mailbox is still game over, due to password resets etc. via e-mail; but "attackers can't intercept your mail" is a more realistic assumption in 2018 than it was when PGP was designed.