Thus the SSL is offering protection for the data in transit, it does not offer any protection for the server itself or for data on the server. It is often possible to break the server system, perhaps over an SSL connection. All of these threats must be considered before selecting an SSL based security approach for any application. Secure E-mail Messaging is an end to end application where data is transferred between two users, typically using a store and forward mechanism. This means that SSL is particularly inappropriate to support secure e-mail, as it only offers protection over the link.
Protection only exists where exchange is between users with accounts on the same e-mail server.
All protection is lost when messages are sent to other Internet users. A Web interface must be used for e-mail. This is acceptable for low volume personal use, but is not a good option for a user that makes extensive use of e-mail, which is now normal in a corporate environment. A Web interface also integrates poorly with the desktop, which makes it awkward or impossible for exchanging secure documents, and generally to support business to business communication. SSL is really not a sensible choice for e-mail security.