gpg encryption failed unusable public key

GPG key problem/question.
GnuPG - User - Re: gpg --batch -ea -r keyid filename.

GPG Configuration Options - Using the GNU Privacy Guard.

As David intimated, the problem here is that gpg doesn't trust the public key you' re using to encrypt. You could sign the key as he explained.
gpg: 5E40F4B6: There is no indication that this key really belongs to the owner gpg: [stdin]: encryption failed: unusable public key the recipient.
enigmail / Forum / Enigmail Support:gpg: skipped "<BrianJRohan.
RSA keys for encryption and in general DSA/RSA/ElGamal-keypairs.

openPGP в России / Форум / Работа с GnuPG / unusable public key.

Re: Error: "unusable public key".

gpg encryption failed unusable public key

gpg encryption failed unusable public key

Fingerprint useless if not self-signed key? | GnuPG | users.
As David intimated, the problem here is that gpg doesn't trust the public key you' re using to encrypt. You could sign the key as he explained.