I got a personal digital certificate and installed it under my e-mail client. I can digitally sign my e-mail but cannot encrypt the messages I send unless I have a copy of the recipient's digital certificate. Why won't my system encrypt my e-mail with myI\u00a0installed a personal digital certificate under my e-mail client. I can digitally sign my e-mail but cannot encrypt messages I send unless I have a copy of the recipient's digital certificate. Why won't my system encrypt my e-mail with my key unless it has a copy of the recipient's digital certificate?Your system doesn't use your key to encrypt e-mail you send, it uses the recipient's public key.A digital certificate has two keys, one public and one private. Messages encrypted with one key can only be decrypted by the other.When you digitally sign e-mail, your system calculates a message digest, which is like a checksum, and encrypts the result using your private key.When someone checks your digital signature by decrypting it with your public key and finds that the message checksum matches the result in the signature, they are assured that you actually sent the e-mail.When you send an encrypted mail message, your system retrieves the recipient's public key from his digital certificate and uses that to encrypt the message. This means the recipient needs the matching private key to decrypt the contents.Signing the mail only certifies that you sent it. Encrypting the mail ensures that only the recipient can read it.