I think the correct words are “digital signature”, and there is a free program PGP who should be able to do it. There is also an EnigMail extension for the Thunderbird mail client, which automatically signs e-mail and verifies e-mail signatures.
Sorry, I don’t understand this topic well, so I can only give you these pointers.
I think the correct words are “digital signature”, and there is a free program PGP who should be able to do it. There is also an EnigMail extension for the Thunderbird mail client, which automatically signs e-mail and verifies e-mail signatures.
Sorry, I don’t understand this topic well, so I can only give you these pointers.