· Change / modification of e-mail content during transit
· Delivery of e-mails to unauthorized recipients
· Copy of e-mail to unauthorized recipient without the knowledge of the correspondents
· "Phishing" e-mail messages, i.e fraudulent email messages that appear to be authentic that direct the recipients to divulge personal confidential data or direct users to the fake websites that exist for the purpose of stealing usernames and passwords.
· The use of forged "from" address for sending unwanted mails and viruses
These kinds of attacks/ risks can be prevented by the use of S/MIME. S/MIME (Secure / Multipurpose Internet Mail Extensions) is a standard for Public Key encryption and signing of e-mail encapsulated in MIME. S/MIME uses digital signatures that digitally sign and encrypt the email. The advantages of S/MIME communication are: