Business Mail service makes it possible to set up calendar synchronizations separately on devices that support CalDAV configuration.
1) Open the Calendar app on your Mac.
2) On the top, from the drop-down options of Calendar, select Accounts.
3) Click on Other CalDAV Account.
4) Enter the details as shown below:
a) Account Type : Manual
b) Username : firstname.lastname@example.org
c) Password : As saved
d) Server Address: dav.flockmail.com
5) On clicking Sign in, it will take a few moments to log you in.
6) You will see your calendar account as shown below.
7) Once done, go back to your calendar and select the Preferences option.
8) Under Account Information, verify the details as shown in the example down below.
9) Navigate to Server Settings and verify the following settings:
a) Internal Server : dav.flockmail.com
b) Server Path : auto filled
c) Port : should be blank
d) Use SSL : should be ticked
You will now have successfully set up your Business Mail calendar via CalDAV on your Mac.