How to Add a Signature to Outlook 365

Whether you're sending client proposals or casual team updates, a well-configured email signature does quiet but consistent work — branding every message you send with your name, title, and contact details. Microsoft 365's Outlook gives you several ways to set this up, and the right approach depends on where and how you're using Outlook.

What an Outlook 365 Signature Actually Does

An email signature in Outlook 365 is a block of text (and optionally images or links) that gets automatically appended to outgoing messages. You can configure it to appear on new emails, replies, forwards, or all three — independently.

Signatures are stored per account, per application. That means the signature you set up in the Outlook desktop app on Windows won't automatically carry over to Outlook on the web (outlook.office.com), and neither will sync to the Outlook mobile app on iOS or Android. Each environment manages its own signature settings.

Adding a Signature in the Outlook Desktop App (Windows)

This is the most fully featured signature editor and the one most people mean when they ask about Outlook 365.

Steps:

1. Open Outlook and select File → Options
2. In the left panel, click Mail
3. Under the Compose messages section, click Signatures…
4. In the Signatures and Stationery window, click New to create a signature
5. Give it a name (e.g., "Work" or "Formal")
6. Type and format your signature in the editor — you can apply fonts, colors, add hyperlinks, and insert images
7. Under Choose default signature, assign which email account uses it, and whether it appears on New Messages and/or Replies/Forwards
8. Click OK to save

You can create multiple signatures and switch between them manually when composing a message — useful if you send both formal external emails and brief internal notes.

Formatting Options in the Desktop Editor

The desktop editor supports rich text formatting: bold, italic, font size, alignment, and inline images. You can paste a logo, add a clickable phone number, or embed a hyperlink to your website. For HTML-formatted signatures (the kind with styled layouts), some teams use an external HTML editor and paste the code directly — though the visual editor handles most common needs without touching HTML.

Adding a Signature in Outlook on the Web 🌐

If you primarily use Outlook through a browser, you'll set up your signature separately there.

Steps:

1. Go to outlook.office.com and sign in
2. Click the Settings gear icon (top-right corner)
3. Select View all Outlook settings at the bottom of the panel
4. Navigate 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
7. Click Save

The web editor also supports basic rich text formatting and image insertion, though it's slightly more limited than the desktop app's editor.

Adding a Signature in Outlook Mobile (iOS & Android)

The mobile app has its own signature setting — by default it shows "Get Outlook for iOS" or a similar default line, which most professionals replace immediately.

Steps:

1. Open the Outlook app and tap your profile icon (top-left)
2. Tap the gear icon (Settings) at the bottom-left
3. Scroll to find Signature
4. Tap your account and type your preferred signature
5. Save by navigating back

Mobile signatures are plain text only — no images, no HTML formatting. If visual branding matters on mobile, the workaround is to keep a minimal text-only version for mobile while using a richer signature in the desktop or web client.

Key Variables That Affect Your Setup

Not every Outlook 365 user has the same experience when configuring signatures. Several factors shape the process:

When Your Signature Isn't Showing Up ✉️

A few common reasons signatures don't appear as expected:

• Reply/forward setting not enabled — the desktop and web clients let you assign signatures separately for new messages vs. replies. Check both dropdowns.
• Wrong account selected — if you have multiple accounts, make sure the signature is assigned to the account you're actively sending from
• Plain text mode — if a message is composed in plain text format, HTML signature formatting won't render
• Organization-managed signatures — your IT or Microsoft 365 admin may be injecting a company-wide signature server-side, which can conflict with or duplicate your personal one

The Part That Depends on Your Setup

The mechanics of adding a signature in Outlook 365 are consistent, but what the right signature configuration looks like for you — how many you need, how they're formatted, whether images are appropriate, and whether your org even allows personal signature customization — depends entirely on your specific role, audience, and IT environment. A solo consultant has completely different needs from someone in a large enterprise where legal disclaimers are auto-appended to every outbound email. Those differences matter more than any particular setting in the editor itself.