Send & Receive Issues

Fix Outlook Sending From Own Account Instead of Shared Mailbox

Maira Mehtab Sep 21, 2026 868 views

Question details

The user has Full Access permission to a shared mailbox in Outlook, but replies are defaulting to their personal email address instead of the shared mailbox address.

Product: Microsoft Outlook / Microsoft 365
Device & OS: not provided
Scenario: Replying to or sending new emails from a connected shared mailbox.
Observed behavior: Emails are being sent from the user's primary personal account rather than the shared mailbox, despite being able to successfully read messages in the shared inbox.

Before you start

Ensure you have the exact email address of the shared mailbox on hand, and confirm whether you have administrator access to the Microsoft 365 admin center if permission changes are required.

Solution 1Recommended

Manually Select the Shared Mailbox in the From Field

Even with correct permissions, Outlook often defaults to your primary account when composing emails. You must manually reveal and select the shared mailbox address in the 'From' dropdown.

By default, the Outlook desktop app sends outgoing messages from your primary account. If you are interacting with a shared mailbox, you must specifically instruct Outlook to send from that address for the first time.

Open a new message or reply

Open Outlook and click 'New Email', or hit 'Reply' on an existing message in the shared mailbox.

Display the From button

If you do not see the 'From' button at the top of your message window, navigate to the 'Options' tab on the ribbon and click 'From' to display the field.

Select Other Email Address

Click the 'From' dropdown button. If the shared mailbox is not listed, select 'Other Email Address...'.

Enter the shared mailbox address

Type the exact email address of the shared mailbox and click 'OK'. Send your email. Outlook will now remember this address in the dropdown for future use.

Automatic Selection: Once you successfully send an email using the shared address, Outlook will typically auto-select it in the future when you are replying to emails while viewing the shared inbox.

Solution 2

Assign Send As Permissions in Microsoft 365 Admin Center

Having 'Full Access' only allows you to read emails. To send emails from the shared mailbox, an administrator must explicitly grant 'Send As' or 'Send on Behalf' permissions.

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Frequently Asked Questions

Why can I read shared mailbox emails but not send them?

Microsoft 365 separates mailbox permissions. 'Full Access' allows you to view and manage the inbox, but you must specifically be granted 'Send As' or 'Send on Behalf' permissions by an administrator to reply from that shared address.

How long does it take for Send As permissions to take effect in Outlook?

After an administrator grants 'Send As' permissions in the Microsoft 365 admin center, it can take anywhere from a few minutes up to 24 hours for the changes to fully sync with the Outlook desktop client.

Will the shared mailbox automatically appear in my Outlook From dropdown?

Usually, it will not appear the first time. You need to click 'From', choose 'Other Email Address', and type the shared mailbox name manually. Once used successfully, it will remain in your dropdown list.

Outlook & Email Problems