Email signature generator › Outlook signature

How to add an HTML signature in Outlook

Outlook is four different programs wearing the same name, and each one handles signatures differently. Here is the path for each, and the formatting rules that keep your signature intact.

New Outlook for Windows and Outlook on the web

1. Open Settings (the gear, top right) → Accounts → Signatures.
2. Click New signature and give it a name — the name is internal, nobody sees it.
3. Click into the editing box and paste with Ctrl + V.
4. Under Select default signatures, choose it for new messages and, separately, for replies. These are two different settings and Outlook does not link them.
5. Click Save. It is easy to miss and nothing is stored until you do.

Classic Outlook for Windows (desktop)

1. File → Options → Mail → Signatures…
2. New, name it, then paste into the Edit signature box.
3. Set the signature for New messages and Replies/forwards in the dropdowns at the top right.
4. OK, then restart Outlook. The classic client caches signatures and sometimes shows the old one until it is reopened.

Outlook on iPhone and Android

The mobile apps only support plain text signatures. They will not render HTML, and there is no setting that changes this. Two workable options:

• Set a short text signature on mobile — name, role, phone — and accept that it differs from desktop.
• Or, if your mailbox is on Microsoft 365 and your administrator has configured a server-side signature, it is appended after the message leaves the device and looks identical from every client. This is the only way to get one consistent HTML signature across desktop and mobile.

Why signatures break specifically in Outlook

Outlook for Windows renders HTML using the Microsoft Word engine rather than a browser engine. In practice that means:

The generator above produces markup that stays inside these limits, which is why it looks the same in Outlook as in Gmail.

Where Outlook keeps signatures on disk

Occasionally the interface is the problem, not the signature — the editor mangles a paste, or a signature refuses to update. On Windows, classic Outlook stores each signature as three files (HTML, RTF and plain text) in:

%APPDATA%\Microsoft\Signatures

Paste that into the address bar of File Explorer and press Enter. Editing the .htm file directly with a text editor gives you complete control over the markup, which is sometimes the fastest route out of a formatting problem. Close Outlook first, or it will overwrite your edit when it next writes the file.

The same folder is worth knowing about for a second reason: it is where you copy signatures from when you move to a new machine. Copying the three files preserves the signature exactly, where re-pasting rarely does.

Roaming signatures, and why yours may not follow you

Microsoft 365 accounts can store signatures in the cloud so they follow you between devices. It sounds like an unambiguous improvement, and it is the reason for two otherwise baffling symptoms:

• A signature you deleted comes back. The cloud copy was resynced over your local change.
• An edit on one machine does not appear on another. One of them is using a local signature and the other the roaming one.

If you are fighting this, work on one device, wait for the sync, and confirm the result in Outlook on the web — that view always shows the server-side copy, so it tells you which version actually won.

Testing it properly, in four minutes

The compose window is not a test. Outlook renders the message you are writing through a slightly different path from the one the recipient sees, so a signature can look right while you type it and wrong on arrival. What actually tests it:

1. Send it to a Gmail address and open it in a browser. This catches markup that only Outlook tolerates.
2. Send it to yourself and open it on your phone. This catches width.
3. Turn images off and read it again. What remains should still be a complete signature.
4. Reply to the message and check the signature does not stack twice or push the quoted text sideways.

Four checks, once. A signature that survives all four will survive nearly every client your recipients use.

Two Outlook-specific annoyances

Images arrive as attachments. Outlook attaches images it considers embedded. Hosting the logo at a public URL rather than pasting the file avoids this.

A blue border appears around the logo. That is the default link border. Adding border:0 to the image removes it — the generator does this already.

Frequently asked questions