Turning off remote content loading is supposed to mitigate against an attack known as EFAIL, which can steal encrypted messages. But the attack can still happen even if you do this.
Source: In Apple Mail, There’s No Protecting PGP-Encrypted Messages
Turning off remote content loading is supposed to mitigate against an attack known as EFAIL, which can steal encrypted messages. But the attack can still happen even if you do this.
Source: In Apple Mail, There’s No Protecting PGP-Encrypted Messages