Open your Community Server portal in a web browser. Sign in to the portal using your administrator or owner account.
Go to the Settings section clicking the icon on the top, select the Integration section in the left-side menu and switch to the Mail Service page.
In the Mail Server IP field, specify the IP address of the machine where Mail Server is installed.
If you have changed the database access password at the previous step, click the Show Advanced Settings link to expand the form where the default access settings are specified. In the Mail Server database password field, specify your new password for the mail_admin user instead of the default one.
Click the Connect button below to verify if all the parameters are set correctly. If the connection between Mail Server and Community Server is successfully established, you will see the 'Successful connection' message.
Click the Save button to apply the settings.
That's all. Now you can click the Configure Mail Server link that appears to go to the Mail Server module. Follow the instructions provided here to connect your mail domain, create a new mailbox and check if the Mail Server works correctly.