SUMMARY

The Apple Calendar client (previously known as iCal) is particular about connecting to CalDAV and CardDAV servers, as it requires the correct configuration of DNS infrastructure. Unfortunately it often does not give meaningful errors when it is unable to connect to CalDAV servers.

To avoid connectivity issues, it is important that you have correctly configured SRV DNS records for the domains offering these services.

This document explains how to configure DNS and then configure the Calendar client. Make sure CalDAV is enabled in the MailEnable administration program.

CONFIGURING DNS INFRASTRUCTURE

When deploying CalDAV and CardDAV services, it is strongly recommended that you configure DNS records to allow clients to locate and connect to these services.  This involves creating specific SRV DNS records so that they are published to clients.

For CalDAV you should configure the following SRV records :

 Example: service record for server without transport layer security

       _caldav._tcp     SRV 0 1 8008  example.com.

  Example: service record for server with transport layer security

       _caldavs._tcp    SRV 0 1 8443 example.com.

Note: In the above example, you should also have a DNS A (Host) record created that equates "example.com" to an IP address.

Important: The Calendar client will use port 8443 by default. If you are having issues connecting from the client, it is suggested that you consider running the server on port 8443 for SSL and 8008 for non-SSL.  You should not use the port number for _caldavs as and _caldav.

Configuring the Apple Calendar client

To set up Calendar to connect via CalDAV, and autodiscover is correctly configured on the server, please follow these steps.

1. Launch the Calendar application
2. Under the Calendar menu, select Preferences..
3. Click Accounts
4. Click + to add a new account
5. Set the Account type as CalDAV
6. Specify the username and password
7. Enter the server address as the domain name that is hosts the SRV records for CalDAV (see earlier section on configuring DNS infrastructure). In the case of the example provided, this would be "example.com".
8. You should then click the Create button. Once this is clicked, the Calendar client will query DNS for example.com and identify the appropriate SRV record. It will use this record to identify the host and port number that is will then connect to.

Manually configuring the Apple Calendar client

If your autodiscovery fails, or you need to manually configure the client, then the steps to manually add a calendar are:

1. Open the Apple Calendar application
2. From the Calendar menu, select Add Account...
3. You will be prompted for the calendar account to add. Select Add CalDAV account... and click Continue
4. In the windows that appears, select Advanced for the Account Type
5. Enter your username for User Name
6. Enter your password for Password
7. Enter either the IP address or the domain name that points to the server running the MailEnable Synchronisation service.
8. In server path enter "/calendar"
9. Set the Port number and the Use SSL checkbox to match what the Synchronisation service is set to
10. Make sure that Kerberos authentication is disabled
11. Click Create to then create the account 

MORE INFORMATION

Detailed information on how DNS records are used to locate CalDAV services can be found at:

https://tools.ietf.org/html/rfc6764