Calendar Interoperability

Calendar Interoperability allows Zoho Calendar users and Microsoft Exchange users to interact with each other and view each other's availability. Using Calendar Interop, Zoho users can check the availability status of Microsoft Exchange users and vice-versa. 

Setting up Calendar Interoperability

As an administrator, if you want your Zoho organization users to find out the availability status of the organization users in Microsoft Exchange, you can set up interoperability between the Calendar users in Zoho and Microsoft Exchange. Depending on the interoperability permission set, the users in both organizations will be able to view the free/ busy status of other users. 

To set up Calendar Interoperability

1. Check your system requirements to set up interoperability between Zoho and Microsoft Exchange.
2. Add email alias for users using a sub-domain. (For organizations using the same domain address for users both in Zoho and Microsoft Exchange)
   • You can skip this step and move to the third step if you are using a different domain address.
3. Configure setup for Zoho Calendar users to look up the availability of Microsoft Exchange users.
4. Configure setup for Microsoft Exchange users to look up the availability of Zoho Calendar users.
5. Verify the setup and check for error messages by performing tests using the troubleshooting tool. 
6. Resolve errors using troubleshooting tips.

System Requirements

The following system requirements are mandatory to perform Interoperability between calendars in Microsoft Exchange and Zoho:

Exchange requirements

• Microsoft Exchange 2013 or 2016 or Exchange Online (Microsoft 365)
• Inbound and outbound internet connectivity for Exchange Web Services (EWS)
• An SSL certificate for the Exchange server. (The certificate should be issued by a trusted public root certificate authority.)
• A Microsoft Exchange role account for Zoho Calendar to access and check the availability of Microsoft Exchange users.

Zoho requirement

A Zoho role account for Microsoft Exchange to access and check the availability of Zoho Calendar users.

Authentication

• Microsoft announced that it will begin disabling Basic authentication for EWS from Oct 1, 2022, and instead provide support for OAuth 2.0. Refer to the Deprecation of Basic authentication in Exchange Online for more details. 
• Zoho Calendar Interoperability supports Basic authentication for on-premises Exchange and OAuth 2.0 for Exchange Online (Microsoft 365).

Add an email alias using a sub-domain

If you use the same email domain address (zylker.com) in both Zoho and Microsoft Exchange, you need to add an alias using a sub-domain to the users in Zoho. There will be a conflict if the domain name used on Microsoft Exchange for Zoho users is the same as the domain used by Microsoft Exchange users since Microsoft Exchange directs the free/busy status request based on the domain name.

It is recommended to use a separate sub-domain to provide the email alias to the users in Zoho. It can be zoho.zylker.com if the domain name is zylker.com. When you configure the settings for Microsoft Exchange, you need to provide the email alias based on the sub-domain in the availability address space for Zoho Calendar in your Exchange server instead of the users' primary email address.

To use an email alias using a sub-domain follow the steps given below:

1. Configure the sub-domain that you are going to use for the email alias of users. The domain address used in Zoho should not be the same as the one used by Microsoft Exchange users.
   • Refer here to configure the domain.
   • Refer here to create an email alias for users.
2. After the domain addition, you need to configure MX records pointing to Zoho for the sub-domain added in the DNS provider settings.
3. You need to use the email alias in the following situations before proceeding to configure the setup for Zoho Calendar users to look up the availability of Exchange users.
   • When setting up mail contacts for Zoho users on Exchange: The primary email address of the Zoho contact in Exchange (usually given in the bold text) should be the email alias based on the subdomain (paula@zoho.zylker.com) and the email address of the contact based on the primary domain (paula@zylker.com) should be added as an alternative email address in Exchange. Refer here, for more details about setting up Zoho users.

     Note:

     You can add the original Exchange email address of the contact as an extra SMTP address for the contact.

   • When adding a new availability space in Exchange: You should use the email alias using the sub-domain when prompted to add contacts in the configuration tool. Learn more.
4. You can send a test email from your Exchange server to a Zoho user using both their primary domain email address (paula@zylker.com) and the email alias using the sub-domain address (paula@zoho.zylker.com).