Personal Outlook signature disappears for shared mailboxes

Problem:

Your personal CodeTwo Outlook (client-side) signature disappears when you change the From address of an email or when replying to an email received in a shared mailbox.

Solution:

This issue is usually caused by adding a shared mailbox (or any other mailbox on behalf of which you want to send emails) as a secondary account in Outlook, e.g. as shown in Fig. 1.

Fig. 1. Shared mailbox added as a secondary account in Outlook for Windows.

If you do that and then select your shared mailbox in the From field when composing an email (see Fig. 2.A), or when you access folders in the mailbox, Outlook makes a full switch to that account. As a result:

• the CodeTwo Outlook Add-in becomes unavailable (unless it's deployed specifically to that shared mailbox), or
• if the add-in is deployed to the shared mailbox, it won't recognize the original user – meaning you cannot send emails on its behalf with your personal signature.

To send an email as or on behalf of another mailbox, always use the Other Email Address option in Outlook (see Fig. 2.B).

Fig. 2. Sending an email from (A) or as / on behalf of (B) a shared mailbox.

To make sure your personal signature is used in all emails, including those sent from shared mailboxes, you need to remove the shared mailbox if it was added as an account and then add it again by assigning delegation rights. You also need to configure the CodeTwo Outlook Add-in to always add users' own email signatures, even if they change the From field and send an email as or on behalf of another user or shared mailbox.

Follow the steps below to configure this in your organization.

• Check CodeTwo add-in settings
• Grant permissions to send emails on behalf of another mailbox
• Mailbox doesn't show up in Outlook after assigning delegate permissions
• (Optional) Remove a secondary mailbox from classic Outlook for Windows

Check CodeTwo add-in settings

1. Sign in to the CodeTwo Admin Panel.
2. Select your Microsoft 365 tenant on the Tenants tab, then go to Outlook add-in.
3. Make sure the Change CodeTwo Outlook (client-side) signatures to match the email address in the From field setting is disabled, as shown in Fig. 3. If not, click the toggle to disable it. Learn more about this setting

   Note that it can take up to 4 hours for this change to propagate.

Fig. 3. To keep your personal signatures in emails sent from shared mailboxes, this option must be disabled.

This ensures you will always get your own signature, even if you change the address in the From field when composing an email.

Grant permissions to send emails on behalf of another mailbox

1. Sign in to the Exchange admin center.
2. Go to Recipients > Mailboxes.
3. Find the (shared) mailbox to which you want to grant a delegate permission and click it to open its settings.
4. Go to the Delegation tab.
5. Under Read and manage (Full Access), click Edit (Fig. 4.).

Fig. 4. Editing the Full Access permission for a mailbox.

6. In the pane that opens, click Add members, select the users you want to grant permission to this mailbox by clicking them, and then click Save (Fig. 5.). Confirm your changes when prompted.

Fig. 5. Assigning mailbox permissions to specific users.

7. Back on the Delegation tab, click Send on behalf (Fig. 6.) and repeat the same actions as in step 6.

   The Send on behalf permission is required to get your personal signatures when sending emails from this mailbox.

Fig. 6. Editing the Send on behalf permission for a mailbox.

After a few minutes, the shared mailbox folders will appear in delegated users' Outlook apps. They may need to restart their Outlook. If they still don't see the mailbox, follow the steps below.

Mailbox doesn't show up in Outlook after assigning delegate permissions

If delegation is set correctly but the shared mailbox doesn't appear in Outlook, the mailbox may need to be added manually to your primary account (not as a separate account).

Classic Outlook

1. Go to File > Account Settings > Account Settings.
2. On the Email tab, select your primary account and click Change (see Fig. 7.).
3. Click More Settings, then go to the Advanced tab.
4. Click Add, enter the shared mailbox name, and click OK.
5. Click OK and exit all dialog boxes.

The shared mailbox folders should now appear in Outlook.

Fig. 7. Adding a delegated mailbox to Outlook for Windows (classic).

New Outlook and OWA

1. Click the ellipsis (...) button next to the Folders section (see Fig. 8.).
2. Select Add shared folder or mailbox.
3. Enter the shared mailbox name and click Add.

The shared mailbox will be added under your primary account folders.

Fig. 8. Adding a shared mailbox to the new Outlook for Windows and OWA.

(Optional) Remove a secondary mailbox from classic Outlook for Windows

1. Go to File > Account Settings > Account Settings.
2. On the Email tab, select your secondary account and click Remove (Fig. 9.), then click OK to confirm.
3. Restart Outlook.

Fig. 9. Removing a secondary email account from Outlook for Windows.

Fig. 10. CodeTwo adds a different signature based on how the email is sent (from or on behalf of another mailbox).