If the OP uses PGP only for signing and signature verification, it's not privacy he's after. If the OP uses PGP for encryption, then his conversation partners

If the OP uses PGP only for signing and signature verification, it's not privacy he's after. If the OP uses PGP for encryption, then his conversation partners use it too, and thus can't use gmail, outlook or yahoo (I am under the impression that desktop outlook has no support for PGP).