It mentions that "Access Providers MUST NOT block users from accessing the external Internet using the SUBMISSION port 587" and that "MUAs SHOULD use the SUBMISSION port for message submission."
Napominje Provajderi ne smeju da zabrane korisnicima pristup spoljašnjem internetu korišćenjem SUBMISSION porta 587 i da MUA bi trebalo da koristi SUBMISSION port za podnošenje poruka.