Microsoft Outlook (classic) for Windows HTML email signature installation guide

This guide covers the classic Outlook desktop app for Windows (the version with the ribbon and a File menu). Classic Outlook stores each signature as a file on your PC, so the most reliable way to install an HTML signature is to edit that file directly.

Using the new Outlook? If your app has a modern look with no File menu, follow our new Outlook for Windows guide instead.

1Create your signature

Design and save your signature in Mirosign. You need an active subscription to copy or download your finished signature.
2Add a blank signature in Outlook
1. In Outlook, go to File → Options → Mail, then click the Signatures button.
2. Click New, name it Mirosign signature and click OK.
3. Choose the correct email account and set the signature for New messages and Replies/forwards. You don’t need to type anything — we’ll replace the contents next. Click OK.
3Open the signature folder

Hold the Ctrl key and click the Signatures button again — this opens the folder where the files are stored. If that doesn’t work, open File Explorer and paste this into the address bar: %AppData%\Microsoft\Signatures
4Replace the file contents
1. Fully quit Outlook (File → Exit). This step matters — Outlook overwrites the file if it’s still open.
2. In the Signatures folder, right-click the .htm file named after your signature and choose Open with → Notepad. (Ignore the .rtf and .txt files.)
3. Select everything in Notepad (Ctrl + A) and delete it.
4. In Mirosign, click Copy HTML, then paste (Ctrl + V) into the empty Notepad file.
5. Save the file (Ctrl + S). Do not rename it or use Save as.
5Done

Reopen Outlook and start a new email — your signature will appear. Send yourself a test email to confirm it looks right before using it day to day.

Design your email signature