Inbox rules of shared mailbox are not showing on classic outlook

Check the shared mailbox’s Settings > Mail > Rules page in Outlook on the web or new Outlook; if the missing rules appear there, manage them there because Classic Outlook cannot display certain rules created or modified in those clients.

This is not documented as a general removal of shared-mailbox rules from Classic Outlook. Microsoft documents a specific, by-design compatibility limitation: a rule can continue running while remaining absent from Classic Outlook’s Rules and Alerts dialog.^1^

Verify the rules

1. Open the shared mailbox in Outlook on the web, preferably in its own browser window.
2. Select Settings > Mail > Rules.
3. Check whether the missing rules are listed and enabled.
4. If listed, edit, run, disable, or delete them there rather than in Classic Outlook.

The documented limitation applies when a rule was created or modified in Outlook on the web or new Outlook and uses one of these:

• Conditions
  • Recipient address contains specified words
  • Message is a new or updated meeting request
  • Message has a classification
• Actions
  • Assign a category
  • Mark as read
  • Set an importance level

Such rules remain active for incoming messages even though Classic Outlook does not display them.^1^

Supported alternative in new Outlook

Since the shared mailbox is already configured separately in Classic Outlook and you have Full Access, there is no reason to add it there again. If using new Outlook is acceptable:

1. Open Settings > Accounts > Shared with me.
2. Expand the shared mailbox.
3. Select Convert if it is currently represented as a shared folder, or + Add if it is not listed.
4. Confirm that it appears under Your accounts.
5. Open Settings > Mail > Rules and select the shared mailbox in the account selector.

Microsoft supports managing shared-mailbox settings—including Rules—when the mailbox is added as an account in new Outlook. Full Access is required, and Microsoft notes that adding a shared mailbox as an account might not yet be available in every new Outlook version.^2^

If the rules are absent everywhere

If they do not appear in Outlook on the web or new Outlook either, the documented Classic visibility limitation does not explain the issue. At that point:

• Test whether the old rules are still processing newly received messages.
• Record the Classic Outlook version from File > Office Account > About Outlook.
• Ask the Microsoft 365 administrator to confirm that Full Access still targets the correct shared mailbox.
• Open a Microsoft 365 support case with the mailbox address redacted, the Outlook build, when the rules disappeared, and whether they are visible or running in Outlook on the web.

Do not delete and recreate all rules unless Classic Outlook displays the specific “There was an error reading the rules from the server” message; Microsoft’s destructive recreate-all-rules workaround applies to that separate known issue, not simply to an empty rules list.^3^

References

1. Inbox rule in Outlook on the web doesn't appear in Outlook for Windows ...
2. Manage shared mailbox settings in new Outlook | Microsoft Support
3. Users get error "There was an error reading the rules from the server" after making changes to rules in classic Outlook | Microsoft Support