Home > CiraHub Support > Calendar Sync > How to Enable Calendar Sync Between an Exchange Server User Mailbox and a Microsoft 365 Mailbox

Are you looking for a way to two-way sync calendars an Exchange Server Mailbox and Microsoft 365 Mailbox? If so, you’ve come to the right place. In this article, we’ll show you how to do just that.

Setting up a calendar sync between an Microsoft 365 mailbox and an Exchange Server user mailbox can help businesses stay on top of all of their crucial tasks and communicate with one another. Without work arounds, scripts or third-party products, it is currently impossible to two-way sync calendars in Microsoft 365. This article will outline how to enable a  two-way calendar sync  between an exchange server user mailbox and a Microsoft 365 Mailbox. 

Two-Way Sync Calendars Between an Exchange Server Mailbox and Microsoft 365 Mailbox

1. Log in to CiraHub. On the Hub & Spoke Setup page, select the Calendars object. Keep in mind that public folders can sync both contacts and calendars. 

Hub and Spoke Setup

2. Next, select the source type of your contact spoke. To sync an Exchange Server Public Folder, click An Exchange Server and select User Mailbox and NEXT (See figure below).

3. Enter your Exchange Server Connector Login, Password, URL, and Exchange Version. If you are running an Exchange Server version dated 2016 or later, always select Exchange 2016 in your connector Settings. 

Entering Exchange Server login details

4. Select the Public Folder Calendar you want to sync from the list. Click on the small arrow in front of a subfolder on the right and choose the item or click the green + button to add a new calendar and click NEXT. (See figure below.)

Select the Mailbox Folder you would like to sync.  

5. Create a name for your first Spoke and click Next. (See figure below.) 

exchange server spoke name

6. Name your Hub, then click CREATE. (See figure below.) 

Naming your hub

7. On the CiraHub dashboard, add a Mailbox Calendar using the +Spoke button. Click Microsoft 365 In my tenant, then User Mailbox, and click NEXT 

Adding a Spoke

8. Choose a Mailbox Calendar and click next, then name your spoke and click CREATE. You should now see two spokes attached to the Hub on the CiraHub dashboard. You can add more spokes as required. (See figure below.)  

CiraHub Dashboard

9. Next, click on each Spoke, select Sync Options and click Allow Hub to create and sync items in this spoke and click SAVE. (See figure below.) 

Modifying Sync Options For Each Spoke


Depending on your organization’s needs, you can utilize a variety of additional sync options, such as private and tentative events, reminders, syncing meetings as appointments, and categorizing data in spokes. You can edit synchronization options for each of your spokes using the options at the bottom of the page. 

10. On the CiraHub Dashboard, click on the Hub, then click Sync Now.

2-Way Sync on CiraHub Dashboard

Learn More About CiraHub!  

CiraHub is a two-way sync platform for shared contacts and calendars for Microsoft 365, Exchange Server, and other Microsoft Enterprise Applications users. This article should help you two-way sync your Exchange mailbox and Microsoft 365 Mailbox calendars together. Click here to learn more about how you can start a CiraHub trial today!