How to Add a Signature in Outlook Office 365

Email signatures do more than sign off a message — they carry your name, title, contact details, and sometimes your brand into every conversation you start. In Outlook for Microsoft 365, signatures are flexible and surprisingly customizable, but the setup process differs depending on which version of Outlook you're using and where you're accessing it. Getting that distinction right is the first step.

Why Outlook Signatures Work the Way They Do

Outlook stores signatures locally on your device, not in the cloud. That means a signature you create in the Outlook desktop app on your work laptop won't automatically appear in Outlook on the web or on your phone. Each platform has its own signature settings, and you'll need to configure them separately.

This is a common source of confusion — someone sets up a polished signature on their desktop, then sends an email from their phone and wonders why it's missing. The fix isn't complicated, but it does require knowing where to look on each platform.

Adding a Signature in the Outlook Desktop App (Windows)

The desktop version of Outlook for Microsoft 365 on Windows gives you the most control over signature formatting.

Step-by-step:

1. Open Outlook and click File in the top menu.
2. Select Options, then choose Mail from the left panel.
3. Click Signatures… — this opens the Signatures and Stationery window.
4. Under Email Signature, click New to create a signature and give it a name.
5. Type and format your signature in the editing box. You can change fonts, add hyperlinks, insert an image (like a logo), and adjust alignment.
6. Under Choose default signature, select which email account the signature applies to, and set defaults for New messages and Replies/forwards separately.
7. Click OK to save.

✍️ You can create multiple signatures — for example, a full signature for new emails and a shorter one for replies — and Outlook lets you set each as a default independently.

Adding a Signature in Outlook on the Web (OWA)

Outlook on the web (sometimes called OWA or accessed via outlook.office.com) has its own signature system.

Step-by-step:

1. Log in to Outlook on the web.
2. Click the Settings gear icon (top right corner).
3. Select View all Outlook settings at the bottom of the panel.
4. Go to Mail → Compose and reply.
5. Under Email signature, type your signature in the text box.
6. Choose whether to automatically include it on new messages and/or replies and forwards.
7. Click Save.

Formatting options here are somewhat more limited than the desktop app — you get basic text styling, links, and images, but you won't have the full range of font controls available in the desktop version.

Adding a Signature in Outlook on Mac

The Mac version of Outlook for Microsoft 365 follows a slightly different path:

1. Open Outlook and go to Outlook → Preferences in the menu bar.
2. Click Signatures.
3. Click the + button to add a new signature.
4. Name it, then edit the content in the panel on the right.
5. Set your defaults for new messages and replies under the Default signatures section.

The Mac interface has been updated over recent versions, so the exact layout may vary slightly depending on which release you're running.

Adding a Signature in the Outlook Mobile App

On iOS and Android, signatures in the Outlook mobile app are plain text only — no images, no HTML formatting, no hyperlinks rendered as clickable text.

To set it up:

1. Open the Outlook app and tap your profile picture or initials (top left).
2. Tap the Settings gear icon (bottom left).
3. Scroll down to find Signature.
4. Type your signature text and tap the back arrow to save.

You can set different signatures for different accounts if you have multiple accounts connected to the app.

Factors That Affect Your Signature Setup 🔧

Rich Formatting, Images, and HTML Signatures

If your organization uses branded email signatures — with logos, social icons, or formatted layouts — the desktop app on Windows is generally where that's best managed. It supports embedded images and basic HTML formatting through its signature editor.

Some organizations manage company-wide signatures centrally through Microsoft 365 admin tools or third-party services, which means individual users may not need to set signatures themselves at all — or may find that a corporate signature is automatically appended server-side regardless of what's in their personal settings.

Common Issues Worth Knowing

• Signature not appearing automatically: Check that you've set a default signature, not just created one. Creating and applying are two different steps.
• Signature shows on desktop but not in replies: New messages and replies/forwards have separate default settings — both need to be configured.
• Images not displaying for recipients: Embedded images sometimes get blocked by recipient email clients. Hosting images externally (via a URL) is generally more reliable than embedding them directly.
• Different signatures on different devices: Expected behavior. Each platform maintains its own settings independently.

The Part That Varies by User

How you should set up your signature — and which platform to prioritize — depends on where you actually send most of your email, what level of formatting your role or organization requires, and whether your IT team manages signatures centrally or leaves it to individual users. A solo freelancer sending from the web will have a different setup than someone in a corporate environment with IT-managed templates and brand guidelines. The steps above cover the mechanics; your own workflow and access level determine which of them apply.