How to Add a Signature in Outlook 365 (Step-by-Step Guide)

Every email you send is a branding opportunity, and your email signature is the easiest place to start. Outlook 365 supports signatures across its desktop app, web client, and mobile apps, but each platform handles signatures differently. The steps for adding a signature in Outlook on Windows look nothing like the steps for Outlook on the web or Outlook mobile, and signatures do not sync between them.

In this guide, we will walk through exactly how to add a signature in every version of Outlook 365. We will also cover why manual signatures become a headache at scale and how email signature software gives IT admins and marketing teams central control over every signature in the organization.

How to Add a Signature in Outlook Desktop (Windows)

The classic Outlook desktop app on Windows gives you the most formatting control over your signature. Here is how to set one up.

1. Open Outlook and click File in the top-left corner of the ribbon.
2. Select Options from the left sidebar.
3. In the Outlook Options window, click Mail on the left.
4. Click the Signatures... button in the "Compose messages" section.
5. In the Signatures and Stationery window, click New.
6. Enter a name for your signature (for example, "Work Signature") and click OK.
7. In the editing area at the bottom, type your signature content. Use the formatting toolbar to adjust fonts, sizes, colors, and alignment.
8. To add an image (such as your company logo), click the image icon in the toolbar and select a file from your computer.
9. To add a hyperlink to text (for example, linking your company name to your website), highlight the text, click the hyperlink icon, and paste the URL.
10. Under Choose default signature, select which email account the signature applies to.
11. Use the New messages dropdown to assign the signature to all new emails.
12. Use the Replies/forwards dropdown to assign a signature (or a shorter version) to replies and forwards.
13. Click OK to save.

Your new signature will now appear automatically at the bottom of every new email you compose from the Outlook desktop app.

Limitations to Keep in Mind

The desktop signature is stored locally on your computer. It will not sync to Outlook on the web, Outlook mobile, or even another Windows PC where you use the same account. If you use Outlook on multiple devices, you will need to recreate the signature on each one.

Also, if your organization uses the "New Outlook" for Windows (the web-based version that Microsoft is rolling out), the signature settings are in a different location. Check the OWA section below for those steps.

How to Add a Signature in Outlook on the Web (OWA)

Outlook on the web (sometimes called OWA or Outlook Web App) has its own signature settings, completely separate from the desktop app. If you primarily use Outlook in a browser, follow these steps.

1. Log in to outlook.office.com or outlook.office365.com.
2. Click the gear icon in the top-right corner to open Settings.
3. At the bottom of the Settings pane, click View all Outlook settings.
4. Navigate to Mail > Compose and reply.
5. Under the Email signature section, you will see a text editor.
6. Type your signature content in the editor. Use the formatting toolbar to style text, add links, and insert images.
7. To add an image, click the image icon in the toolbar. You can insert an image from a URL or upload one inline.
8. Check the box for Automatically include my signature on new messages I compose if you want it added by default.
9. Check the box for Automatically include my signature on messages I forward or reply to if desired.
10. Click Save.

Starting with newer versions of OWA, Microsoft allows you to create multiple signatures and switch between them. Look for the option to name and manage multiple signatures in the same Compose and reply settings panel.

Key Differences from Desktop

The web signature is stored in the cloud with your Microsoft 365 account, so it will follow you to any browser. However, it does not carry over to the Outlook desktop app or mobile apps. You are managing a separate signature for each platform.

How to Add a Signature in Outlook Mobile (iOS & Android)

Outlook mobile supports signatures, but with significant limitations compared to desktop and web. Here is how to set one up.

On iOS (iPhone and iPad)

1. Open the Outlook app and tap the home icon (or your profile picture) in the top-left corner.
2. Tap the gear icon at the bottom to open Settings.
3. Scroll down to the Mail section and tap Signature.
4. If you have multiple accounts, you can toggle Per Account Signature to set a different signature for each account.
5. Type your signature text in the text field.
6. Tap the back arrow to save.

On Android

1. Open the Outlook app and tap the home icon (or your profile picture) in the top-left corner.
2. Tap the gear icon to open Settings.
3. Tap your email account under the account list.
4. Tap Signature.
5. Enter your signature text.
6. Tap the checkmark to save.

The Mobile Limitation

Outlook mobile signatures are plain text only. You cannot add images, logos, hyperlinks, or HTML formatting. This means your carefully designed desktop signature with your company logo, social media icons, and promotional banner will not carry over to mobile. Recipients will see a basic text-only version instead.

For organizations that care about consistent branding, this is one of the biggest pain points with Outlook's built-in signature handling. We will cover how to solve this later in the article.

How to Add a Signature in Outlook for Mac

Outlook for Mac has its own signature interface that differs from the Windows version. Here is how to access it.

1. Open Outlook for Mac.
2. In the top menu bar, click Outlook > Preferences (on newer versions of macOS, this may appear as Outlook > Settings).
3. Click Signatures.
4. Click the + (plus) button to create a new signature.
5. Give the signature a name in the "Signature Name" field.
6. In the editing area, type and format your signature. The toolbar provides options for fonts, colors, sizes, images, and links.
7. Under Choose default signature, select the account, then choose the signature for new messages and replies/forwards using the dropdown menus.
8. Close the Preferences window. Your changes save automatically.

Like the Windows desktop app, the Mac signature is stored locally. It does not sync to Outlook on the web, Outlook mobile, or your Windows PC.

Why Manual Signatures Don't Scale

Setting up a signature in Outlook is straightforward for a single user on a single device. But for organizations with dozens, hundreds, or thousands of employees, the manual approach creates real problems.

Every Client Requires Separate Setup

As you have seen, Outlook desktop, Outlook on the web, Outlook mobile, and Outlook for Mac all store signatures independently. An employee who uses Outlook on their work PC, checks email in a browser, and reads messages on their phone needs to set up the same signature three or four times. In practice, most people only set it up once and leave the others blank or outdated.

No Central Control for IT or Marketing

When signatures are managed by individual employees, there is no way for IT or marketing to enforce consistent branding. Logos go out of date. Employees use the wrong font or forget to include their title. Legal disclaimers get deleted. Promotional banners that marketing carefully designed never make it into half the team's signatures.

If your organization needs consistent email signature management, relying on manual setup across four different Outlook clients is not a viable strategy.

No Rich Signatures on Mobile

Outlook mobile's plain-text-only limitation means there is no native way to deliver branded, HTML-formatted signatures on phones. Given that a large percentage of business email is now read and sent from mobile devices, this gap affects how your brand shows up in a significant portion of your email communication.

Signatures Go Stale

Employees change roles, phone numbers change, and marketing campaigns rotate. Without a central system, there is no way to push updates. You are relying on every employee to manually update their signature across every client whenever something changes. For a deeper look at how to solve these challenges with Microsoft 365 specifically, see our guide to Office 365 email signatures.

How to Manage Signatures Company-Wide in Office 365

If manual signatures do not work for your organization, there are several approaches to centralized management within the Microsoft 365 ecosystem.

Transport Rules in Exchange Online

Microsoft 365 admins can use mail flow rules (also called transport rules) in the Exchange admin center to append HTML signatures to outgoing emails. This works server-side, so the signature is added after the email leaves the user's client. That means it works regardless of which device or app the sender uses.

The downsides: transport rules are limited in their formatting options, difficult to manage for large organizations with many departments, and do not allow the sender to see the signature before hitting send. They also strip any client-side signature, which can lead to duplicate signatures if not configured carefully.

PowerShell Scripts

For organizations comfortable with scripting, PowerShell can pull user data from Active Directory and programmatically generate signatures. This approach is powerful but requires technical expertise to set up and maintain. It also typically only works for Outlook desktop (by placing signature files in the correct local directory) and does not solve the mobile or OWA problem.

We have a detailed walkthrough of this approach in our post on bootstrapping Outlook signatures with PowerShell and Active Directory.

Server-Side Solutions Like Opensense

A third-party email signature management platform like Opensense takes a different approach. Opensense integrates directly with Microsoft 365 at the server level, applying signatures to every outgoing email regardless of whether it was sent from Outlook desktop, OWA, Outlook mobile, Apple Mail, or any other client.

This gives IT admins and marketing teams full control: they design the signature template once, map fields to directory attributes (name, title, phone, department), and every email gets a consistent, branded signature automatically. Updates roll out instantly without any action required from employees.

For a detailed comparison of these options, check out our IT admin guide to Office 365 email signature management and our broader guide on how to set up email signatures in Office 365.

FAQ

Can I use the same signature across all Outlook apps?

No. Outlook desktop (Windows), Outlook for Mac, Outlook on the web, and Outlook mobile each store signatures separately. There is no built-in sync feature that carries your signature from one client to another. You need to manually create and maintain your signature in each app. The only way to apply a single signature across all clients is to use a server-side solution that adds the signature after the email is sent, such as Exchange transport rules or a platform like Opensense.

Can I add an image to my Outlook 365 signature?

Yes, on desktop and web. Both Outlook desktop (Windows and Mac) and Outlook on the web support images in signatures, including logos, headshots, and promotional banners. You can insert images using the formatting toolbar in the signature editor. However, Outlook mobile (iOS and Android) only supports plain text signatures. There is no way to add images, logos, or formatted HTML to a mobile signature using the built-in settings.

How do I set a default signature for new emails vs. replies?

Each Outlook client lets you assign different signatures for new messages and replies or forwards. In Outlook desktop (Windows), this option is in File > Options > Mail > Signatures under "Choose default signature." In Outlook on the web, the checkboxes in the Compose and reply settings let you choose whether to include your signature on new messages, replies, and forwards. In Outlook for Mac, the Preferences > Signatures panel has dropdown menus for both new messages and replies. Outlook mobile does not offer this distinction; the same signature is applied to all outgoing messages.

Can my IT admin set my signature for me?

Not directly through Outlook's built-in settings. Outlook does not have an admin console for pushing signatures to individual users. However, IT admins have two main options. First, they can use Exchange Online transport rules to append a signature to all outgoing mail at the server level. Second, they can use a third-party email signature management tool like Opensense, which integrates with Microsoft 365 and Active Directory to automatically apply branded signatures to every email. Both approaches remove the need for individual employees to configure anything themselves.