Setting up SMTP Authentication in Apple (Mac) Mail for Existing Mailbox
1. Open Mail and go to Mail --> Preferences
2. Select the "Accounts" tab and select the Account you wish to configure.
3. Make sure the "Account Information" tab is selected. At the bottom of
this screen there is a drop-down list for Outgoing Mail Server (SMTP).
Select "Edit SMTP Server List".
4. To add a new SMTP server to the list click the plus icon (+) at the
bottom of the window. Make sure the "Account Information" tab is
selected.
5. Fill in anything you wish for "Description" (some name that will help
you remember which SMTP server these settings refer to, such as your
domain name) and under "Server Name" enter mail.example.com (replace
"example.com" with your actual domain name).
6. Now click on the "Advanced" tab. For "Authentication" select
"Password" and then enter your email username and password in the form.
7. You may want to select "Use custom port". Default SMTP port is 25,
but if that does not work you might want to use 587 as the Cartika servers listen on these alternative ports to provide a
workaround for those ISPs that block Port 25.
8. Click "OK" to save your settings.