& kmail; expects that your PGP binary is called pgp; in the case of GnuPG, it expects the binary to be called gpg. If this is not the case for you, just make a symlink.
O & kmail; espera que o binario do PGP se chame pgp; no caso de GnuPG espera que o binario se chame gpg. Se non é o caso, simplemente cree unha ligazón simbólica.