What's the difference between Outlook 365 and Outlook web?

Outlook 365 is the desktop app you install on your computer. Outlook web runs in a browser. They have separate signature settings — changes in one don't sync to the other.

Can I use an HTML signature in the Outlook desktop app?

Yes, but with limitations. Outlook desktop uses the Word HTML rendering engine, which strips many modern CSS properties. DropSig templates use table layouts that are compatible with this engine.

How do I add a signature to only some emails?

Set "New messages" and "Replies/forwards" to "(none)" in the Signatures dialog. Then manually insert a signature when composing: go to Insert → Signature in the email toolbar.

Does my Outlook 365 signature sync across devices?

Signatures set in the desktop app are stored locally on that machine. They don't sync to other computers or to Outlook web. Set up signatures separately on each device.

How to Add an Email Signature in Outlook 365 Desktop

This guide covers the classic Outlook desktop app on Windows — the one you install from Microsoft 365 (formerly Office 365). The interface is different from Outlook on the web, with its own dedicated Signatures dialog. Here's how to set it up.

Before you start

You'll need a signature to paste. Already have one? Skip to step 1.

Create your signature first →

Step-by-step setup

Open the Outlook desktop app. Click "File" in the top-left menu bar, then select "Options" near the bottom of the left sidebar.

In the Outlook Options dialog, click "Mail" in the left sidebar.

In the Compose messages section, click the "Signatures…" button. The Signatures and Stationery dialog will open.

Click "New" to create a new signature. Enter a name like "Work" or "Main" and click OK.

In DropSig, click "Copy Signature". This copies the HTML-formatted signature to your clipboard.

Click inside the signature editing area in the Signatures dialog and paste (Ctrl+V). The signature will appear with its formatting.

Pro tip: The Outlook desktop editor supports richer HTML than the web version. Most DropSig templates paste cleanly here.

On the right side of the dialog, use the "New messages" and "Replies/forwards" dropdowns to select your new signature as the default.

Click "OK" to close the dialog, then "OK" again to close Options. Create a new email to confirm your signature appears automatically.

Common issues

Signature looks different from DropSig preview

Outlook desktop renders HTML using the Word engine, which has limited CSS support. Avoid floats, flexbox, and complex positioning. DropSig templates use table-based layouts that work well in Outlook.

Can't find the Signatures button

The Signatures button is in File → Options → Mail → Compose messages section. If you don't see it, make sure you're in the "Mail" section, not "General".

Read the full fix →

Image appears as a red X

This usually means the image URL is blocked or the email client has image loading disabled. Check that images are loading in your browser, and consider embedding the image directly in Outlook.

FAQ

Need a signature to paste?

Create one free in 30 seconds →

Free Outlook 365 (Desktop) Signature Generator Outlook signature not showing Html email signature Add logo to email signature

Last verified: March 2026