Of the similarly-aged protocols, I think it's the most difficult (which is not saying much).
SMTP and HTTP can be pretty easily done by hand, which makes them more accessible to a person learning the protocols themselves.
DNS the protocol is simple, but I do think there's something to be said for how complex it is if you want to say, set up your own domain from which to reliably send e-mail.
SMTP and HTTP can be pretty easily done by hand, which makes them more accessible to a person learning the protocols themselves.
DNS the protocol is simple, but I do think there's something to be said for how complex it is if you want to say, set up your own domain from which to reliably send e-mail.