In order to ensure end to end security within Zendesk Sell, we require that all connecting email accounts have SSL or TLS security enabled. If you're trying to connect your email using ports that are not secure, you will receive the error message "connection not secure".
You can check if your SSL/TLS certificate is properly set up using the free online SSLShopper service. When checking the certificate, make sure to to add the port number at the end. The search you perform on SSLShopper should look like the following - "getbase.com:443" - without quotations.
Note that your SSL certificates cannot be self signed. Your security is very important to us and certificates must come from a trusted, third party source.
Once you enable SSL security for your email account, you will then be able to connect your email with Sell and begin sending and receiving emails directly within the system.