Base64 encryption algorithm considered three major problems: first is encrypted; the second is the complexity and efficiency of the encryption algorithm; third, how to deal with the transmission. Encrypt is necessary, however the main purpose is not to encrypt the users to send secure Email but to achieve the effect of fail to understand the contents directly. The encryption algorithm for this purpose, its complexity and efficiency can not be too high or too low. MIME protocol and the protocol used to send Email address is used to send and receive Email but not to safely send and receive Email. Therefore, the complexity of the algorithm and the efficiency must be higher, otherwise they will be resource-intensive because of sending Email.