You have found this KB because you received an SSL error when checking your mail.
In most cases such error is shown because something did go wrong in the authentication handshake between your computer and the server. The error is a bit confusing as it in most cases says it is an SSL Error, although this is an old name for a new(er) protocol used named TLS ; all versions of SSL are already obsolete and insecure, nowadays we use TLS, also in TLS we have versions and currently there are 2 already out of date and have security issues.
Other as with running an old computer program a TLS version which is old often means there is a MAJOR security issue with it. This is the case with TLS1.0 and TLS1.1 ; currently the most common version is TLS1.2
If you have an old version of OS (i.e. Windows 7) or some older android system or an older version of mail software, you may receive an SSL Error, in our logs this usually translates to the following:
TLS handshaking: SSL_accept() failed: error:140760FC:SSL routines:SSL23_GET_CLIENT_HELLO:unknown protocol
This error shows us that the client is using either version 1.0 or 1.1 on a new server, older servers due to older OS versions and installations may have still allowed some of these, but as servers are upgraded and/or replaced you may see this error sooner or later if you did not update your devices to a secure version.
For Windows 7 there is a patch (we did not test this, but it may help) https://support.microsoft.com/en-us/help/3140245/update-to-enable-tls-1-1-and-tls-1-2-as-default-secure-protocols-in-wi
The only advice we can give is ; please make sure that if you use mail software or an older version of OS that you keep up to date or upgrade, especially if you connect those devices to the internet (as you do if you check your mail on it).
