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Fix Office 365 Mailbox Delegation Not Working Error

Published By Mohit Jha
Nimisha Ramesh
Approved By Nimisha Ramesh
Published On March 19th, 2024
Reading Time 5 Minutes Reading

Kristi Taylor: “I am the global admin for my company. I used Office 365 Exchange Admin Center to delegate myself full access to a user’s mailbox. However, when I attempted to open that mailbox, I received an error: Office 365 mailbox delegation not working. Does anyone know the cause of the problem? How to fix this error? Any help or suggestion would be of great help.”

Does the query seem familiar to you? Are you also looking answer to the same problem? Well, here you will find an answer to the same problem. So, let us begin.

The sharing of data is done in numerous ways. In Office 365, there are two ways of sharing data:

  • One is folder-sharing
  • The second is providing delegate access

In folder sharing, a user can view the folders but, does not have the authority to send or receive on the behalf of another person.

Additionally in the delegate access, a user can reply to meeting requests or send emails from their side to some other user.

Delegation access is used when an admin wants a single account to be accessed by multiple users. The post deals with delegate access and the error that occurs when Office 365 mailbox delegation not working.

Assign Exchange Online Mailbox Delegation

When a user is handling some other person’s account in addition to their account, it is advised to add the other account to their account. By doing this, both the accounts can be easily accessed and managed. But, this can be done only when the owner of the other mailbox permits you to do so.

The mailbox owner should grant the administrator folder visible permission on the root folder of the Office 365 mailbox. To assign mailbox permissions in Office 365, a user needs to go through the following steps:

  1. Navigate to the Exchange mailbox root folder and right-click on it
  2. From the given options, select Folder permissions
  3. Select the delegate’s name to whom you want to assign permissions
  4. In Permissions, select the Folder visible from Others option
  5. Click the OK button to save the changes made and assign permissions

What If the Outlook Delegate Access Not Working?

The points should be taken into consideration for proper working of delegate access:

Case1: The user can see the data in the mailbox but, cannot act on behalf of the other users

In this scenario, the owner of the mailbox is required to give full access permissions in Office 365 to other users. This can be done by following these steps:

  1. Use Windows PowerShell together with O365
  2. Type this command in the PowerShell
    Add-MailboxPermission –Identity “Mailbox name” –User “Mailbox Name” –AccessRights FullAccess
  3. Doing this will enable the user to access full permissions.

Case2: User cannot send emails on behalf of other users

Check the below-mentioned steps to enable the user to send emails on behalf of the owner of the mailboxes:

  1. Login to the O365 Exchange Admin Center
  2. Click on Recipients. Then, double-click on the display name. Press on Shared
  3. Click Mailbox delegation to add up the user under the Send As option

Also Read : Explore different Reasons behind Data Loss in Office 365

Case3: If any miscellaneous issue occurs and Outlook delegate access not working then

  • Let us assume that there is a problem with the mailbox. The user is confused and does not know where to start, the first thing to do is check the settings
  • Confirm which mailboxes are assigned delegation permission. And check all the permissions that are granted to the other users
  • Check if the permissions are properly granted or not. If not, then the cause of the problem is linked to Microsoft Outlook
  • The possible solution that will work in this case is to repair or reconfigure your profile

Tip: Do not directly jump on repairing the profile. Consider this solution as the last option. Also, before granting the permissions to another user, consider taking the local backup of the O365 mailboxes.

Best Solution: Office 365 Mailbox Delegation Not Working

The professional solution to avoid the error: Office 365 mailbox delegation full access not working is to use a third-party tool like Office 365 or Exchange Online Backup. This tool helps in creating the backup of Office 365 mailbox. Also, the files are recovered from corruption and can be saved in other formats. According to the experts, it is the master solution to resolve the issue.

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Final Words

It happens many times a user has granted full access permissions to other users but, it is not working. The error prompts on-screen showing: Office 365 mailbox delegation not working. Methods to resolve the error are discussed. A professional tool to fix the issue is also described.

Frequently Asked Questions

Q  How to enable the other user to send emails in place of the owner of the mailboxes?

A-  Follow the below steps sequentially:-

  1. Sign in to the O365 EAC.
  2. Open Recipients and double-click on the display name then hit on Shared.
  3. Click on the Mailbox delegation to add the user under the Send As option.

Q How to assign the permissions to other users in Office 365 using PowerShell?

A – Execute the below command to assign permissions to other users.

Add-MailboxPermission –Identity “Mailbox name” –User “Mailbox Name” –AccessRights FullAccess