`git-secret-tell` receives an email address as an input, searches for the `gpg`-key in the `gpg`'s `homedir` by this email, then imports a person's public key into the `git-secret`'s inner keychain. From this moment this person can encrypt new files with the keyring which contains their key. But they cannot decrypt the old files, which were already encrypted without their key. They should be reencrypted with the new keyring by someone, who has the unencrypted files.
