CryptPlugin is a plugin for Eudora Mail Clients Version 3.x, 4.x and 5.x . CryptPlugin will encrypt a given message using RSA RC2 block cipher or RC4 stream cipher. First you choose a password and a encryption algorithm, and CryptPlugin will automatically encrypt and encode the selected message. After this, the message can only decrypted and read by a recipient who has already CryptPlugin installed and knows the encryption key. CryptPlugin is an easy and fast way to add powerful encryption/decryption capabilities to Eudora mail.