---
sourceDocument: Zurich Employee Service Management
sourceDocumentLink: https://www.servicenow.com/docs/r/zurich/employee-service-management

 Release :

    - zurich

ft:locale :

    - en-US

ft:publication_title :

    - Zurich Employee Service Management

ft:clusterId :

    - emplsm

bundleId :

    - emplsm

workflow :

    - Employee


---

# Microsoft Exchange On-Premises - Calendar synchronization

# Microsoft Exchange On-Premises - Calendar synchronization {#ariaid-title1}

* Release version: Zurich
* 
* Updated July 31, 2025
* 
* ![](https://www.servicenow.com/docs/portal-asset/ico-clock) 5 minutes to read

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## Summary of Microsoft Exchange On-Premises - Calendar synchronization

This feature enables ServiceNow customers to synchronize workplace reservations between the Workplace Reservation Management application and Microsoft Exchange On-Premises calendars.
Unlike cloud-based calendars, the on-premises Exchange server is accessible only within the local organizational network.
Synchronization is facilitated through a MID server installed locally, which communicates between ServiceNow and the on-premises Exchange server using the Microsoft EWS calendar processor.
Show full answer Show less  

## Key Features

* **Bidirectional synchronization:** Reservations created in Workplace Reservation Management are synchronized to the on-premises Exchange calendar, and vice versa.
* **Delta synchronization:** Incremental calendar changes are synchronized based on synchronization tokens, optimizing performance by retrieving only updates since the last sync.
* **MID server communication:** The MID server installed locally enables secure and continuous communication with the on-premises Exchange server.
* **Scheduled sync job:** A configurable scheduled job named *WSDRS Sync Calendar items* runs periodically (default every 5 minutes) to fetch calendar updates and create corresponding reservations in ServiceNow.
* **Strict mode:** When enabled, calendar events are sent to a general email address rather than directly to employees' calendars, requiring employees to use the Workplace Reservation Management application to make changes.
* **Past reservations synchronization:** Supports syncing reservations from a specified historical date range with configurable limits to avoid overloading the system.
* **No request mode:** Allows administrators to validate event payloads in JSON format without sending API calls to Exchange, useful for testing and troubleshooting.

## Practical Implementation Steps

* Install and configure the Microsoft Exchange Server spoke and the MID server in the local environment where Exchange On-Premises is hosted.
* Create connection and credential aliases in ServiceNow to securely connect to the on-premises Exchange calendar provider.
* Configure Microsoft Exchange On-Premises as a calendar provider within the Workplace Calendar Synchronization application.
* Activate reservable sync configuration records to initiate synchronization flows and generate synchronization tokens.
* Enable and schedule the *WSDRS Sync Calendar items* job to run at desired intervals for continuous synchronization.
* Optionally enable strict mode or synchronize past reservations based on organizational requirements.

## Key Outcomes

* Seamless synchronization of workplace reservations between ServiceNow and on-premises Exchange calendars, ensuring consistent booking information across platforms.
* Efficient incremental updates reduce load and improve synchronization speed.
* Secure communication through MID server supports on-premises infrastructure constraints.
* Flexible synchronization options, including strict mode and past reservation sync, provide adaptability to different organizational policies and scenarios.
* Validation capabilities via no request mode enhance configuration accuracy without impacting live data.  
Create a connection with Microsoft Exchange On-Premises and synchronize reservations made using the Workplace Reservation Management application. You can synchronize all the reservations that are made using the Workplace Reservation Management to the On-Premises calendar and vice versa. The reservation synchronization from an On-Premises calendar to the Workplace Reservation Management is performed using various approaches like subscriptions, synchronization tokens, events, and occurrences.
The Microsoft Exchange On-Premises, unlike other calendar providers, isn't accessible online. The provider is remote and is accessible only by the organization locally. To synchronize calendar reservations with this on-premise setup, the Workplace Calendar Synchronization application enables you to communicate using the MID server. A MID server is installed in the same local setup where the Microsoft Exchange On-Premises is installed. This way, a communication can be established with the MID server and communicate frequently. To support the on-premises calendar provider, a new calendar processor, Microsoft EWS is supported in the Workplace Calendar Synchronization application.

1. Connect MID server with ServiceNow®.
2. Create a connection and credential alias.
{#ms-exchange-on-prem-calendar-synchronization__ol_h2f_y1s_sxb}  
Important:  
The Workplace Reservations for Microsoft Outlook Add-in application does not support Microsoft Exchange On-Premises.

## Synchronization from Workplace Reservation Management to Microsoft Exchange On-Premises {#ms-exchange-on-prem-calendar-synchronization__section_jqh_5xj_5xb}

Synchronize reservations to the on-premises calendar from Workplace Reservation Management by communicating using the MID server.

* Install [Microsoft Exchange Server Spoke](https://www.servicenow.com/docs/access?context=msexchangeserver-spoke&version=zurich&pubname=zurich-integrate-applications&ft:locale=en-US).
* [Set up the Microsoft Exchange Server spoke](https://www.servicenow.com/docs/access?context=setup-msexchange&version=zurich&pubname=zurich-integrate-applications&ft:locale=en-US)
* [Connect Microsoft Exchange On-Premises MID server with ServiceNow](https://www.servicenow.com/docs/0fYvXNDG3TnXHJ6Xmn1ogA "Configure connection between the MID server of Microsoft Exchange On-Premises and ServiceNow to synchronize reservations.")
* After configuring the MID server, create a connection and credential alias to connect it with the calendar provider. For more information, refer to [Create a Connection and credential alias for Microsoft Exchange On-Premises](https://www.servicenow.com/docs/qywZ1jzIWjE3e08UGYgYrg "Establish a connection and credential alias for Microsoft Exchange On-Premises so that you can synchronize reservations. Ensure that the values for the connection and credentials alias are set as specified.").
* After setting up the connection and credential aliases, configure Microsoft Exchange On-Premises as a calendar provider. For more information, refer to [Configure Microsoft Exchange On-Premises as calendar provider](https://www.servicenow.com/docs/kzlqutF5nnmBAaiTMW98EA "Set Microsoft Exchange On-Premises as calendar provider to sync reservations. Specify the calendar processor, the sync-related settings, and strict mode preference."). To support the on-premises calendar provider, a new calendar processor, Microsoft EWS is added.
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## Synchronization from Microsoft Exchange On-Premises calendar to Workplace Reservation Management {#ms-exchange-on-prem-calendar-synchronization__section_vxk_xqb_5xb}

The reservation synchronization from the Microsoft Exchange On-Premises calendar to the Reservation portal is done by running a timely scheduled job, WSDRS Sync Calendar items.  
An approach called, Delta synchronization is used by the Workplace Calendar Synchronization application. With Delta synchronization, you retrieve only the incremental changes made on a resource email id of the calendar using a reference point called as synchronization token. That is, for each room (each reservable sync record), linked to the on-premises calendar provider you get the synchronization tokens, which are the reference points to get the update from the calendar in increments.

* Based on the Page size, Sync batch size and the Sync batch interval, the information is retrieved by the synchronization tokens. For example, if you specified the values as 5, 500, and 60 respectively (in the previous fields). It means that you can raise 500 requests in an interval of 60 seconds. The synchronization results five changes in a page.
* When you create a reservable sync configuration record under the on-premises calendar, you must ensure that is activated.
* When the sync record is activated, a flow is triggered and a synchronization token for that reservable synchronization record is created in the Sync Deltas module.
* The scheduled job, WSDRS Sync Calendar items, is provided with the application to get the latest changes for all the active reservable sync configurations. The scheduled job is set to False by default and it must be enabled to start synchronizing. By default, the scheduled job is set to run for every five minutes. However, you can set the scheduled job time as you want. At any time, you can also manually execute it.
* The changes made on the reservable sync configurations are created as events in the Events module. The application creates Create, Update, Delete, Read, and Retrieve attendees events for Microsoft Exchange On-Premises calendar.
* For each sync record, an event is created. Depending on the page size specified on the calendar provider, the changes are displayed. If there are any pending changes, it is displayed during the next scheduled job run.
* The API that is used to get the synchronization tokens, saves the response in the Response field of the event. The API provides changes made on a single reservation, multi-reservation, and the parent recurring reservation.
* Using the response created by the API, a reservation is created in the Workplace Reservation Management application.
* With every scheduled job run, the synchronization token is also updated which is used as the reference point for the next synchronization.
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## Strict mode {#ms-exchange-on-prem-calendar-synchronization__section_l5t_3hk_5xb}

The Workplace Calendar Synchronization application enables you to configure your connections and configurations with Microsoft Exchange On-Premises in strict mode as well. In strict mode, events are not directly created in an employee's calendar, instead, they are sent to a general email address. Employees are invited to the
event. You can specify a strict mode email id through which you want to sync reservations. Employees can only make changes using the Workplace Reservation Management application.

To enable strict mode, you can enable the Strict mode option in the while configuring the on-premises calendar provide. The requesters are considered as invitees.

## Synchronizing past reservations {#ms-exchange-on-prem-calendar-synchronization__section_d2z_gxc_5xb}

The Workplace Calendar Synchronization enables you to also synchronize reservations made in the past. You can specify the date and time range in the Sync start date time and Sync end date time fields. For the on-premises calendar, the following conditions must be met to sync past reservations:

* The calendar provider that is the Microsoft Exchange On-Premises calendar provider that you configured must be active.
* The Synchronize past reservations field must be selected.
* The reservable sync configuration for which you want to sync past reservations must be active.

{#ms-exchange-on-prem-calendar-synchronization__ul_e1g_q1d_5xb}  
Note:  
Ensure that the reservations that you want to sync from the past are not above 1000. If in cases the expected number of past events are more than 1000, it is recommended to modify the system property sn_wsd_rsvsync.ewsPastSyncPeriodInMonths. Specify the value in months keeping in mind the expected past reservations. A single sync syncs reservations from those many months. Ensure that the specified number of months do not have more than 1000 reservations per room/resource.

## 'No request' handling {#ms-exchange-on-prem-calendar-synchronization__section_e23_jdd_5xb}

No request is a mechanism to validate the generated syntax of the payload of an event created for the calendar. But, instead of sending the event to the calendar provider, it is only created. The admin can validate the payload
content of the event (JSON) to ensure that is generated as expected. 'No request' ensures that the application does not make any API calls to the calendar provider when you create, update, or cancel a reservation in the Workplace Reservation Management application.