An SSL Certificate is a file issued by a trusted third party that verifies you have connected to a legitimate server and not an imposter trying to steal your data. When an SSL connection is made with a server, the server provides the certificate to the computer connecting to it. The computer then analyzes the certificate to verify the identity of the server.

All SSL certificates eventually expire and must be reissued. When this happens, your computer or email application may not recognize the new one. In some cases, you’ll be prompted to approve the certificate manually or cancel the connection; in others, it simply won’t connect.

Each email application handles this a bit differently, so we’ll show you how to accept the new SSL in your application.