Outlook adds the signature of the account you are writing from, whatever the From field says. When you start an email in your own mailbox and switch From to info@ or sales@, Outlook still uses your mailbox's settings, so the email carries your personal signature or no signature at all. To give the shared mailbox its own signature, add it to Outlook as a separate account and set the signature on that account, or have an admin stamp one on with a mail flow rule.
The signature follows the account you write from
On January 1, 2026, someone on Exchange Online asked on Microsoft Q&A how to make a shared mailbox's signature apply when someone picks its address in the From field. In Outlook on the web, the signature worked when the shared mailbox was opened with "Open another mailbox". When the person stayed in their own mailbox and changed the From address, the signature was missing.
Four days later, a second user asked how to set individual signatures in shared mailboxes that others could not pick by mistake, and ten people marked it as their question too. The asker explained what changed: classic Outlook added each person's own signature for the shared mailbox, with their name. New Outlook offers one general signature, or a list of personal ones that anyone can pick from a menu, so someone can send with a colleague's name.
The answers on both threads agree on the cause. Vasil Michev, a Microsoft MVP and volunteer moderator, wrote that the signature works only when the shared mailbox is opened in "direct" mode, as an account of its own. A moderator from Microsoft's external staff explained that the message is still sent from the primary mailbox session, so its settings apply.
Fix 1: add the shared mailbox as an account
This gives info@ a signature box of its own, in the account picker next to your personal account.
New Outlook for Windows. Microsoft's page on shared mailbox settings in new Outlook gives the steps:
- Open "Shared with me" from the File tab (Account info), or from Settings > Accounts.
- If the mailbox is listed, expand it and select "Convert". If it is not, select "+ Add" and follow the prompts.
- Then go to Settings > Accounts > Signatures. Microsoft's signature guide says that with more than one account, you select the account the signature belongs to. Pick the shared mailbox, add its signature, and use the checkboxes to set it for new messages and for replies and forwards.
Two limits, both from Microsoft: you need Full Access permission to the mailbox, which an admin grants, and adding a mailbox as an account "may not be available in your version of new Outlook at this time".
Classic Outlook. Add the shared mailbox through File > Add account, as the MVP answer suggests. Classic Outlook lets you have "different signatures for each email account", so once the shared mailbox is an account, File > Options > Mail > Signatures lets you set its default signatures.
Outlook on the web. Open the mailbox with your name > "Open another mailbox" and set its signature in that window's settings. That is the setup the first asker tested.
Then start each email from the shared account.
Fix 2: keep a second signature and pick it
If you can't add the mailbox as an account, make a second signature in your own account, named something like "info@", and pick it from the Signature menu whenever you send from the shared address. It costs one click per email and relies on people remembering. In new Outlook that list is also how one person ends up sending with another's signature, the complaint in the second thread.
Fix 3: an admin adds the signature on the server
A Microsoft 365 admin can add text to every email the shared mailbox sends with a mail flow rule. Microsoft's guide to organization-wide disclaimers, signatures and footers has the steps in the Exchange admin center: Mail flow > Rules > "Add a rule" > "Apply disclaimers". Set the condition to the shared mailbox as the sender and paste the signature as HTML.
What to know before you rely on it:
- It is added after the email leaves Outlook. The person writing doesn't see it in the compose window.
- Images need a web address. The rule takes HTML with an
imgtag, so the logo has to be hosted online. The Microsoft moderator on the first thread gave the same warning. - Stop it repeating. By default the rule runs on every message in a thread. Microsoft says to add an exception that looks for a phrase from the signature, so it goes on the first email only.
- Tokens fill from the sender. The rule can insert values such as
%%DisplayName%%and%%Phone%%. Microsoft says they use "values from the sender", so when the shared mailbox is the sender, they fill with its details. - Test it first. Microsoft recommends a test mode before you set the rule to "Enforce".
Pick the fix by who signs the email
- The team signs as the team (a shop's info@, an office's bookings@): add the mailbox as an account and give it one signature.
- Each person signs with their own name from a shared address: the second asker says classic Outlook did this per person. In new Outlook, each person picks their own signature from the list, or the company uses an add-in.
- No one should be able to forget it: the mail flow rule, set up once by whoever runs your Microsoft 365.
Build the signature for Outlook's editor
Whichever box it goes in, the signature is easier to paste when it is built for Outlook. Signatoro's free generator makes one with no account: one table with inline styles, the format Outlook's editor keeps when you paste, and a logo hosted at a public web address with a fixed width. "Copy signature" copies it for a signature box. For a mail flow rule, "HTML" > "Copy HTML" copies the code the rule takes. The new Outlook guide and the classic Outlook guide have the paste steps.
Questions
Why does my shared mailbox email show my personal signature?
You wrote it from your own mailbox and changed the From address. Outlook applies the signature of the account you compose in, so your personal signature comes along. Write from the shared mailbox added as its own account instead.
Can Outlook add a signature automatically when I pick info@ in the From field?
Outlook's own settings can't do it. The answers on Microsoft Q&A say the signature follows the account you write from. A mail flow rule, which adds it on the server, is the way to cover every email from that address.
Do I need Full Access to the shared mailbox?
To add it as an account in new Outlook, yes. Microsoft says the permission is granted by your organization's IT admin.
Will a mail flow rule add the signature twice in a long thread?
It will unless you add the exception. Microsoft's guide says to make the rule skip messages that already contain a phrase from the signature.
Sources
Read on November 2, 2026:
- Email signature for shared email box (Microsoft Q&A, January 2026)
- Managing Shared Mailbox Signatures (Microsoft Q&A, January 2026)
- Manage shared mailbox settings in new Outlook (Microsoft Support)
- Open and use a shared mailbox in Outlook (Microsoft Support)
- Create and add an email signature in Outlook (Microsoft Support)
- Organization-wide message disclaimers, signatures, footers, or headers in Exchange Online (Microsoft Learn)