If the Exchange or Office 365 integration was set to dedicated mailbox & delegation, delegate access must be granted on a user-by-user basis. Delegation grants permissions to the dedicated mailbox to create events on behalf of Users, and by default, can only read your meeting requests and responses. 

To grant delegate access, you will need the email address of your organization’s dedicated Reschedge mailbox.

After setting up delegate access, visit the Diagnostics section and confirm that all tests pass.

1. Delegate access in Outlook

If you’re using Outlook, the first two steps depend on your Outlook client version. The further configuration steps are the same in all versions.

In Outlook 2010 and up:

1. Click on the File tab
2. Click on the Account Settings drop-down menu, and choose Delegate Access

In Outlook 2003 & 2007:

1. From the Tools drop-down menu, select Options 

2. A dialog box will appear.  Select the Delegates tab

Further steps in all Outlook versions:

3. If the Reschedge user is not present, click on the Add button. If the dedicated mailbox is already present, select it and click on Permissions.
   If Add doesn’t appear, an active connection might not exist between Outlook and Exchange. The Outlook status bar displays the connection status.

4. In the Add Users dialog box, choose the dedicated Reschedge mailbox, click Add and then click OK

5. The Delegate Permissions window will appear. Choose Editor permissions for the Calendar, check the box that reads "Delegate receives copies of meeting-related messages sent to me", and click OK  

6. In the Delegates window, select the option to deliver meeting requests to "My delegates and me", and click OK

2. Delegate access in Office 365

1. From your Office 365 calendar, right click on your main calendar and choose Sharing permissions

2. Enter and select the Reschedge dedicated mailbox in the “Share with” field. If needed, click on Search Directory to locate that mailbox in your Office 365 Exchange server

3. Choose “Delegate” from the sharing permissions drop-down menu, and click Send
4. Right-click on your main calendar again, and choose Permissions…
5. On the Delegates section, select that invitations will be sent to “Both my delegate and me” and click Save

3. Delegate access using Windows PowerShell (for advanced Users):

The Exchange admin within your organization can also grant delegate access on behalf of each User. This can save Users the hassle of configuring delegate access.

Delegate access permissions can be granted using Windows PowerShell. 

In Windows PowerShell enter:

[PS] C:\Windows\system32>Set-MailboxFolderPermission -Identity enduser@domain.com:\Calendar -User reschedgeuser@domain.com -AccessRights Editor