How to add a signature in Outlook for Mac (new and legacy)

How do you create a signature in Outlook for Mac?

From the Outlook menu in the menu bar, at the top of the screen. The steps below follow Microsoft's Outlook for Mac guide:

1. On the Outlook menu, select Settings, then Signatures under Mail.
2. Select the + button to add a signature, then type its name.
3. In the editor, type the signature text and format it: font, style, size, color.
4. Under See more items (…), add a picture or logo, a link or a table if needed.
5. Close the Signatures window.

An "Untitled" signature is sometimes already in the list: rename it rather than leave an empty one lying around. The window has no Save button; closing it is enough.

Why isn't my signature added automatically?

Because a new signature is not linked to any account until you set it as the default. In the same Signatures window, under Set default signature:

1. Choose the email account.
2. Choose the signature for the For new messages option.
3. Choose the one for the For replies or forwards option, or none if you prefer replies without a signature.
4. Repeat for each account, then close the window.

Microsoft spells it out: with several accounts, the default signature is set separately for each one. That is what lets your work address send the full block with the logo while another stays plain, and it is also the most common reason a reply goes out unsigned.

What about legacy Outlook for Mac?

The path is almost the same: Outlook > Settings, then Signatures under E-mail. Double-click Untitled to name the signature, or add one with +; pictures come from the Photo Browser or Picture from file. The default is chosen under Choose default signature, with the New messages and Replies/forwards lists, account by account.

Before you set it up, though, check that it still works for you. Microsoft states that starting October 2026, legacy Outlook for Mac stops working against Exchange Online mailboxes: it relied on EWS, which Microsoft retired on October 1, 2026. It keeps working with Exchange on-premises until October 9, 2029. For a Microsoft 365 mailbox, switch with the Legacy Outlook toggle in the app; what this means for signature tools is covered in the guide on the end of EWS.

How do you edit or rename an existing signature?

Go back to Outlook > Settings > Signatures, select the signature under Signature name, then Edit. Change the text or the image, then close the window. Renaming a signature does not change which accounts use it, but check Set default signature after a cleanup: a deleted signature leaves the account without one.

To insert a signature manually in a single message, click in the message body, then Signature on the ribbon (sometimes under See more items). If the button is missing, Microsoft says you can add it by customizing the toolbar.

How do you add a logo that doesn't vanish on the recipient's side?

Insert the image file from the editor (See more items, then the picture) rather than pasting it from a browser or Word: a paste carries hidden formatting that throws off the alignment. Prefer a PNG or JPG to an SVG, which Outlook does not display everywhere.

On the recipient's side, a missing logo has several possible causes: images blocked until they click "show images", a file that is too heavy, an image hosted on a server they cannot reach. The missing signature image guide goes through them, the banner size tool gives dimensions by screen, and the signature checker catches these problems before your clients do. Also send yourself a test to a Gmail address and an Outlook address.

Should you edit the signature files in the Library folder?

No. Microsoft documents neither the location nor the format of Outlook for Mac signature files, and other vendors' guides do not all give the same folder under ~/Library/Group Containers/UBF8T346G9.Office/. A file edited or copied by hand may be ignored, or overwritten by the next update. To change a signature, use Settings > Signatures; to install one on several machines, use a tool built for that.

Does the Mac signature show up on Windows, the web or the iPhone?

Don't count on it. The roaming signatures Microsoft documents apply to Outlook for Windows, with a Microsoft 365 or Outlook.com mailbox; the page does not mention the Mac. A signature built on a PC or in Outlook on the web can therefore be missing on the Mac, and the other way around.

On iPhone and Android, the Outlook app has its own setting: Settings, then Signature under Mail, with a Per Account Signature option. Microsoft explains it on its mobile signature page. The Mac and mobile guide shows how to get the same signature on both.

How do you give every Mac on the team the same signature?

By hand, you repeat the steps above on every Mac, for every account, then again at every change of title, phone number or banner. With a few machines, that works. Beyond that, each new hire gets the version of whoever set them up.

An Outlook add-in solves it differently: it inserts the signature while the message is being written, in Outlook for Mac as on Windows, the web, iPhone and Android, with nothing to set up on the machine. That is how ATOM Signatures works: one template, contact details pulled from the Microsoft 365 directory, the signature visible in the draft, and no email rerouted through a third-party server. The steps are in the guide to deploying a signature across the organization, and the comparison with the native Microsoft 365 options shows their limits. For the other Outlook clients, see how to add a signature in Outlook, client by client.

Frequently asked questions