Microsoft 365 Group: why can I send a new email from the group but cannot forward emails from the group inbox?

Question

Hello,

I’m investigating an issue with a Microsoft 365 Group email behavior.

We are using a Microsoft 365 Group (not a Shared Mailbox) that has an email address

assigned to it (e.g., ******@company.com).

Observed behavior:

• Sending a NEW email directly from the group interface works correctly.
• The message is sent successfully from the group address.
• However, when opening an email in the group Inbox and clicking “Forward”, Outlook Web returns the error: “An internal server error occurred. The operation failed.”

This issue is consistently reproducible.

Users are members/owners of the group and are using Outlook Web.

Question:

Is this expected behavior / limitation of Microsoft 365 Groups?

Is it supported that groups can send new emails but cannot forward emails from the group inbox?

Are there any supported configuration options or workarounds to enable forwarding,

or is converting to a Shared Mailbox the only recommended solution?

Thank you.

Answer 1

Hi Saltanat Kolesnichenko

Thank you for reaching out to Microsoft Q&A forum

Based on your description, I have conducted some research, and I think the following information may help you.

Regarding your questions

1/ Is this expected behavior / limitation of Microsoft 365 Groups?

Actually, Microsoft has not published any official document mention about this behavior is the known limitation, however, as far as I know, the "Internal server error" when attempting to forward a conversation from a Microsoft 365 Group via Outlook Web (OWA) is a behavior reported by many users. The reason is Microsoft 365 Groups are designed for threaded conversations, not individual message management like a traditional inbox. The "Forward" action on a group conversation thread is not supported in the same way as a standard email message.

Some users acknowledged that while "Send As" works, the "Forward" button in OWA fails with "An internal server error occurred" because the underlying architecture treats group items as conversation threads rather than independent forwardable messages.

You can read here for more information: https://techcommunity.microsoft.com/discussions/to-do/sync-problems/146864

2. Is it supported that groups can send new emails but cannot forward emails from the group inbox?

Yes, this distinction is supported by the permission model.

• Sending New Emails: This works because you have correctly assigned Send As permissions. This allows a user to generate a new outbound message spoofing the group address. This is a specific Exchange Online permission explicitly for sending, not for managing existing inbox items.
• Forwarding Emails: Forwarding requires the ability to take an existing item from the group's storage and relay it. Since Group mailboxes do not have a standard "Sent Items" or "Drafts" folder for individual users in the same way a Shared Mailbox does, the web interface often fails to process the "Forward" command on the conversation object.

3. Configuration options or workarounds (vs. using a Shared Mailbox):

Currently, there is no built-in toggle in Microsoft 365 Groups to enable standard email forwarding from the group inbox. You likely cannot "fix" the OWA Forward button error directly as it is an architectural limitation, but here are the supported paths:

Option A:

• Use Outlook Desktop: Users reporting this error in OWA often find that dragging the email into their personal "Drafts" folder in the Outlook Desktop client allows them to forward it successfully.
• Reply & Add Recipient: Instead of forwarding, users can "Reply to All" and manually add the external recipient to the CC line.
• Transport Rules (Admin): If the goal is auto-forwarding, admins can create mail flow rules to redirect group email, though this does not solve manual ad-hoc forwarding.

Link reference: https://learn.microsoft.com/en-us/exchange/security-and-compliance/mail-flow-rules/mail-flow-rules

Option B: Convert to Shared Mailbox

If your users need to Forward, Categorize, or Flag emails, converting to a Shared Mailbox is the recommended solution. Shared Mailboxes are designed specifically for this "Help Desk" or "info@" style workflow.

4. What is the recommended approach to migrate?

In this situation, you can try creating a new Shared Mailbox. Then export the Group’s mailbox content using Microsoft 365 eDiscovery (Content Search) or PowerShell, and import the data into the Shared Mailbox using Outlook or the Microsoft 365 Import service.

5. Do I need to remove or change the Group’s email address first?

Yes. You must either rename or delete the Microsoft 365 Group to release its email address before assigning it to the new Shared Mailbox. If deleted, the group enters a soft-deleted state for up to 30 days, so you may need to wait or permanently delete it via PowerShell.

6. Are there supported tools or steps to preserve email history?

Yes. Use Microsoft Purview eDiscovery (Content Search) to export the Group’s mailbox to a PST file. Then import the PST into the Shared Mailbox using Outlook or the Microsoft 365 Import service. Alternatively, PowerShell (New-MailboxRestoreRequest) can be used if the Group is soft-deleted.

Hope my answer will help you.

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Answer 2

In Microsoft 365 Groups, users can send new emails from the group interface, but there are known limitations regarding forwarding emails from the group inbox. The error message you are encountering, "An internal server error occurred. The operation failed," indicates that this behavior is not supported for forwarding emails directly from the group inbox.

Currently, Microsoft 365 Groups do not support forwarding emails from the group inbox, which is likely the reason for the error you are experiencing. The recommended workaround is to convert the group to a Shared Mailbox if forwarding functionality is essential for your workflow. Shared Mailboxes have more flexible email handling capabilities, including the ability to forward emails.

Therefore, it is expected behavior that groups can send new emails but cannot forward emails from the group inbox, and converting to a Shared Mailbox would be the only recommended solution to enable forwarding.

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References:

• Manage Microsoft 365 Groups with PowerShell

Answer 3

Question:

Is there a supported way to convert an existing Microsoft 365 Group into a

Shared Mailbox while keeping the same email address?

If direct conversion is not supported:

• What is the recommended Microsoft approach to migrate from a Group to a Shared Mailbox?
• Is it required to remove or change the email address on the Group first?
• Are there any supported tools or steps to preserve email history during this process?