For browsers
Google Chrome :Chrome browser version 4 to Chrome browser version 29 doesn't suppport. Chrome browser version 30 to Chrome browser version 70 supports SECURITY TLS 1.2.
Mozilla Firefox :Mozilla Firefox browser version 2 to Mozilla Firefox browser version 26 doesn't support. Mozilla Firefox browser version 27 to Mozilla Firefox browser version 63 supports SECURITY TLS 1.2.
Internet Explorer : Internet Explorer browser version 6 and Internet Explorer browser version 10 doesn't support. Internet Explorer browser version 11 supports SECURITY TLS 1.2.
Safari :Safari browser version 3.1 to 11.1 doesn't support. Safari browser version 12 supports SECURITY TLS 1.2.
Microsoft Edge : Microsoft Edge browser version 12 to 15 doesn't support. Microsoft Edge browser version 16 to 18 supports SECURITY TLS 1.2.
Opera : Opera version 10.1 to 38 doesn't support. Opera version 39 to 53 supports SECURITY TLS 1.2.

Mail clients
You may run into connectivity issues if you have any of the following mail client software installed on your local machine

Windows 7 (you can manually enable TLS 1.2 in the control panel which should fix the problem)
Windows XP and older
Apple Mail 9.3 and older
Mac OS 10.11 (El Capitan) and older
Mac OS Mojave Version & Mail App 12.2 (may require manual port settings)
Microsoft Entourage (all versions)
Outlook for Mac 2012 and older

Outlook for Windows 2013 (pre SP1) and older
Thunderbird 27 and older
Windows Live Mail

Android 4.3 and earlier
iOS 10 and above are OK.