How do you give a shared mailbox its own email signature? Decide that the signature belongs to the address the email is sent from, not to the person typing it, and then give each shared mailbox a signature of its own. Done that way, mail from info@ or accounts@ carries the team's details every time, whoever is on duty and whichever device they use.
A personal Outlook signature belongs to a person's own account. When that person sends from a shared mailbox, Outlook may add their own signature, the wrong one for the address, or nothing at all, depending on the app and how the mailbox was added. Multiply that by everyone who covers the inbox, and the sales address sends in five different styles.
Microsoft 365 has two permissions for sending from an address that is not your own:
The permission changes what the recipient sees in the From line, and so it changes which signature makes sense. With Send As, the team's signature is the natural choice. With Send on Behalf, you might want either.
Footer365 adds signatures as mail leaves Microsoft 365, and it follows one rule: the signature belongs to the sending address.
| Sending from | Signature used |
|---|---|
| Your own mailbox or alias | Your own |
| A shared mailbox such as info@ | The shared mailbox's |
| A mail-enabled group address | The group's, with personal lines such as job title left out |
On the way out, Footer365 uses the sending address that Exchange Online passes with the message. For Send As, that is the mailbox being sent from. For Send on Behalf, send a test to an outside address and look at which signature arrives, because it follows the address Exchange passes on.
If a mailbox is brand new and does not appear yet, run Sync now under Directory, Users & groups. Our troubleshooting guide to the wrong signature on a shared mailbox or delegate covers each of these in more detail.
If you also use the Footer365 add-in to show the signature while people write, it switches signature when someone changes the From field to a shared mailbox, a room or equipment mailbox, or a group they belong to.
It deliberately does not switch when someone writes from another person's own mailbox, for example as their assistant. Footer365 does not know who has been given permission to send as whom, so the add-in uses the writer's own signature rather than show one person's details on another person's behalf.
Not with Footer365. You pay for user mailboxes, those with an Exchange licence, and a shared mailbox has no licence. Shared, room and equipment mailboxes get signatures without counting as seats. Our article on shared mailboxes and seats explains how each account is counted, and where to see the figure.
Pick your three busiest shared mailboxes, send one email from each to an address outside your organisation, and look at what arrives. If any came without the team's details, a rule per mailbox fixes it for everyone who covers that inbox from then on.
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