How to add an email signature in Outlook

Before you start: have the signature ready

Outlook's signature editor is a basic rich-text box. Building a signature in it produces messy HTML that looks different in Gmail and on phones. Make the signature elsewhere, copy it as rich text, and paste it in.

If you do not have one yet, the free signature generator makes a clean, table-based signature with your logo in about two minutes and has a Copy signature button that puts the right thing on the clipboard.

New Outlook for Windows and Outlook on the web

These two share the same settings and the signature is stored with your account, so it follows you to every device signed in to that mailbox.

1. Copy your signature.
2. Click Settings (the gear icon, top right).
3. Go to Accounts → Signatures. On older builds it is Mail → Compose and reply.
4. Click New signature, give it a name, click into the editor and paste.
5. Under Select default signatures, choose it for New messages and for Replies/forwards.
6. Click Save.

You can keep several signatures and switch with Insert → Signature while writing.

Classic Outlook for Windows

1. Copy your signature.
2. Open File → Options → Mail and click Signatures…
3. Click New, name it, click into the edit box and paste.
4. In Choose default signature, pick the email account, then set New messages and Replies/forwards.
5. Click OK.

Prefer a file? Classic Outlook reads signatures from a folder. Press Win+R, enter %APPDATA%\Microsoft\Signatures, and drop an .htm file there (the generator's Download .htm button produces one). It appears in the Signatures dialog the next time you open it.

Outlook for Mac

1. Copy your signature.
2. Open Outlook → Settings (⌘+,) and click Signatures.
3. Click +, name the signature, click into the box and paste. Close the window to save.
4. Under Choose default signature, select it for your account.

Outlook on iPhone and Android

The mobile app has its own signature setting and it is text only: Settings → Signature. Bold, italic and links survive; images and layout do not. If new Outlook or Outlook on the web is set up on the same account, the mobile app does not use that signature either.

This is the main reason organisations move the signature off the device entirely. A server-side tool such as UnifySig adds the signature after the message is sent, so the phone, the web and the desktop all produce the same result. The phone signature guide covers every mobile app.

Common problems

The logo shows a red X or does not load

Outlook only reliably displays images that are embedded in the signature or hosted at a public web address. A logo pasted from a website usually works; one dragged from a folder sometimes does not. Re-paste the signature from the generator, or link to a logo on your website.

Line spacing doubles

The editor treats Enter as a new paragraph with a blank line. Signatures built with tables (as the generator does) are not affected; if you edited by hand, use Shift+Enter for line breaks.

It appears on new messages but not replies

Replies and forwards have their own default. Set both in the signature settings, as in the steps above.

Different signature on another computer

Classic Outlook stores signatures on the PC. New Outlook and Outlook on the web store them with the account. If you use both, set the signature in both places, or use a tool that applies it centrally.

Setting signatures for a whole company

Copying a signature onto every laptop and phone does not scale, and it drifts the first time someone changes title. UnifySig connects to Microsoft 365, fills each person's signature from Entra ID and applies it to every mailbox server-side, including shared mailboxes and mobile. Design once, assign by group, done.