Recent updates have introduced a technical requirement that changes the minimum TLS version a client can use to now be v1.2. This version is already 12 years old, so any modern client will support it.

Old windows 7 and 8 clients do support it, but require a setting enabled as per https://docs.microsoft.com/en-us/archive/blogs/schrimsher/enabling-tls-1-1-and-1-2-in-outlook-on-windows-7

A quote regarding the change:  “There has been talk of disabling TLS 1.0 for quite some time.  The original deadline was June 30, 2016, but this has been extended until June 30, 2018.”

Email Account Settings
Select the mail client you currently use, and go through the steps to set the correct Email Settings.

KCI Mail Info
Ports
incoming email port = POP3 995 + SSL
IMAP4 993 + SSL
outgoing email port = 587 + TLS
mail.kci.net for incoming and outgoing server.