Encryption cryptosystems have been adapted to inject some degree of security into e-mail:

S/MIME builds on the MULTIPURPOSE Internet Mail Extensions (MIME) encoding format by adding encryption and authentication

PRIVACY Enhanced Mail (PEM) was proposed by the Internet Engineering Task Force (IETF) as a STANDARD to function with the public KEY cryptosystems

PEM uses 3DES symmetric key encryption and RSA for key exchanges and digital signatures

Pretty Good Privacy (PGP) was developed by Phil Zimmerman and uses the IDEA Cipher along with RSA for key exchange.

Encryption cryptosystems have been adapted to inject some degree of security into e-mail:

S/MIME builds on the Multipurpose Internet Mail Extensions (MIME) encoding format by adding encryption and authentication

Privacy Enhanced Mail (PEM) was proposed by the Internet Engineering Task Force (IETF) as a standard to function with the public key cryptosystems

PEM uses 3DES symmetric key encryption and RSA for key exchanges and digital signatures

Pretty Good Privacy (PGP) was developed by Phil Zimmerman and uses the IDEA Cipher along with RSA for key exchange.