SSL and TLS are not actually monolithic encryption entities that you either use or do not use to connect securely to email servers, web sites, and other systems. SSL and TLS are evolving protocols which have many nuances to how they may be configured. The “version” of the protocol you are using and the nuances of the configuration directly affect the security achievable through your connections.
Some people use the terms SSL and TLS interchangeably, but TLS (version 1.0 and beyond) is actually the successor of SSL (version 3.0). … see SSL versus TLS – what is the difference? In 2014 we have seen that SSL v3 is very weak and should not be used going forward by anyone (see the POODLE attacks, for example), TLS v1.0 or higher should be used.
Among the many configuration nuances of SSL and TLS, which “ciphers” are permitted have the greatest impact on security. A “cipher” defines the specific encryption algorithm to be used, the secure hashing (message fingerprinting / authentication) algorithm to be used, and other related things. Some ciphers that have long been used, such as RC4, have become weak over time and should not be used in secure environments.
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