Mail Setup window opens. Click on Email Accounts

Double click on the iMAP or PoP3 email you want to edit:

The Change Account window opens.

Make sure that both Incoming mail server and Outgoing mail server

have host.realtime-server.com set as shown below.
After changes have been made click Next.

After pressing next, mail will test the new settings;

Last screen is the verification screen;

Press Finish
You are done.