Give mailbox permissions to another Microsoft 365 user - Admin help
As the admin, you may have company requirements to allow some users access to another user's mailbox. For example, you may want to enable an assistant to send or read email from their manager's mailbox. Or you may want to give one of your users the ability to send email on behalf of another user.
If you're looking for information about creating and managing shared mailboxes, check out Create a shared mailbox.
Tip
If you need help with the steps in this topic, consider working with a Microsoft small business specialist. With Business Assist, you and your employees get around-the-clock access to small business specialists as you grow your business, from onboarding to everyday use.
Set up mailbox permissions
The first step to setting up permissions is deciding which actions you want to allow the other user to take in the given mailbox. You can allow a user to read emails from the mailbox, send emails on behalf of another user, and send emails as if they were sent from that mailbox. Permissions can only be set up within the current organization. It's not possible to set up mailbox permissions for users in another organization. Read the sections below for the task you want to complete:
Note
Once you've set up the permissions, it can take up to 60 minutes for the changes to propagate through the system and be in effect.
Access another person's mailbox
There are a few different ways to access a mailbox once you've given permission and access. See the Access another person's mailbox article for the steps.
Send email from another user's mailbox
In the admin center, go to the Users > Active users page.
Select the name of the user (from whom you plan to give a sending permission) to open their properties pane.
On the Mail tab, select Send as permissions.
Select Add permissions, then choose the name of the person who you want this user to be able to send as.
Select Add.
In the admin center, go to the Users > Active users page.
Select the user you want, expand Mail Settings, and then Select Edit next to Mailbox permissions.
Next to Send as, select Edit.
Select Add permissions, then choose the name of the person who you want this user to be able to send as.
Select Add.
Read email in another user's mailbox
In the admin center, go to the Users > Active users page.
Select the name of the user (whose mailbox you want to allow to be read) to open their properties pane.
On the Mail tab, select Read and manage permissions.
Select Add permissions, then choose the name of the user or users that you want to allow to read email from this mailbox.
Select Add.
Note
Read and Manage permissions are called Full Access permission when granted in the Exchange admin center. This permission allows the assigned user mailbox to read as well as manage emails in the user mailbox on which the permission is assigned. Full Access permission does not grant Send as or Send on behalf permissions.
In the admin center, go to the Users > Active users page.
Select the user you want, expand Mail Settings, and then select Edit next to Mailbox permissions.
Next to Read and manage, select Edit.
Select Add permissions, then choose the name of the user or users that you want to allow to read email from this mailbox.
Select Add.
Send email on behalf of another user
In the admin center, go to the Users > Active users page.
Select the name of the user (from whom you plan to give a Send on behalf permission) to open their properties pane.
On the Mail tab, select Send on behalf of permissions.
Select Add permissions, then choose the name of the user or users that you want to allow to send email on behalf of this mailbox.
Select Add.
In the admin center, go to the Users > Active users page.
Select the user you want, expand Mail Settings, and then select Edit next to Mailbox permissions.
Next to Send on behalf, select Edit.
Select Add permissions, then choose the name of the user or users that you want to allow to send email on behalf of this mailbox.
Select Add.
Note
The Send As and Send on Behalf permissions do not work in Outlook Desktop client with the HiddenFromAddressListsEnabled parameter on the mailbox set to True, since they require the mailbox to be visible in Outlook via the Global Address List.
Related content
Manage another person's mail and calendar items (article)
Send email from another person or group (article)
Change a user name and email address (video)
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