Remember that it is not safe at all if you sign the message to make sure that the receiver will get the correct key: there can be a man-in-the-middle attack, as somebody can change the key and sign the message with that other key. That is why the recipient should verify the attached key by checking the key's fingerprint against the one he received in a secure way from you; have a look at the PGP documentation for further details.
Lembre que non é nada seguro se asina a mensaxe asegurarse de que o destinatario recibe a chave correcta: pode haber un ataque "do home no medio" e alguén pode alterar a chave e asinar a mensaxe con esoutra chave. É por iso polo que o destinatario debería verificar a chave anexada comprobando a pegada da chave contra a que recibiu de maneira segura; consulte a documentación do PGP para máis detalles.