Termination of support for TLS 1.0 / 1.1
Update: Termination of support hast been postponed! We will end the support for TLS 1.0 and TLS 1.1 in our webhosting environments as of March 31, 2020 since Apple, Google, Microsoft, and Mozilla jointly announced they would deprecate TLS 1.0 and 1.1 in future. Please make sure that you are using up-to-date software supporting TLS 1.2 to connect to your mailbox(es) to ensure continuous operation. Up-to-date web browsers of the major suppliers support TLS 1.2.
TLS (Transport Layer Security) is used to secure connections on the web and provides the ability to form connections that are confidential, authenticated, and tamper-proof. This has made it a big focus of security research, and over the years, a number of bugs have been found in the protocol. Revisions have been published to address these flaws.
The impact of removing the old protocols should not be too substantial. The usage figures for the old TLS versions 1.0 and 1.1 are 1.4 percent (Firefox) and below 1.0 percent (the other three vendors) of all secure connections. The current recommendation is that web sites switch to TLS 1.2 (which happens to be the minimum required for HTTP 2.0) and offer only a limited, modern set of encryption algorithms and authentication schemes. TLS 1.3 was recently finalized, but is not yet widely used.