How to setup a default signature for a Shared Mailbox in Exchange and Outlook

Question

In this scenario, we have users who use a primary user mailbox as well as a shared mailbox. They wish to have default signatures for each mailbox. However, when going into Outlook Options > Mail > Signatures, only the user mailbox appears as selectable for configuring a signature. The shared mailbox does not have a way to select a default signature.

Does anyone know how to configure a default signature for a Shared Mailbox?

Any help would be greatly appreciated.

Answer 1

Outlook on the Desktop requires a mailbox to be added explicitly (manually in the instructions below). Not implicitly via Auto Provisioning. Only then are you able to set it a signature as a default.

Instructions on how to do it are here: https://support.microsoft.com/en-gb/office/open-and-use-a-shared-mailbox-in-outlook-d94a8e9e-21f1-4240-808b-de9c9c088afd

What if it didn't work?

If your admin only recently added you to a shared mailbox, it may take a few minutes before the shared mailbox appears. Wait a bit and

then close and restart Outlook again.

If that didn't work, then manually add the shared mailbox to Outlook:

    Open Outlook.

    Choose the File tab in the ribbon.

    Choose Account Settings, then select Account Settings from the menu.

    Select the Email tab.

    Make sure the correct account is highlighted, then choose Change.

    Choose More Settings > Advanced > Add.

    Type the shared email address, such as info@contoso.com.

    Choose OK > OK.

    Choose Next > Finish > Close.

Answer 2

Based on my knowledge, you could add a disclaimer as a signature to the shared mailbox by creating a transport rule(Append the HTML disclaimer / Apply a HTML disclaimer to the message). The following rule is for your reference:

If you grant the Send As permission of the shared mailbox to users, after they "send as" the shared mailbox, the recipients will receive emails with a disclaimer(signature):