Outlook signature double-spaced? Here's the actual fix

Updated June 2026

You set up a signature that looks fine everywhere else, but in Outlook every line has a blank line after it. Name, gap, job title, gap, phone number, gap. This is one of the most common signature complaints, and the cause is specific and fixable.

Why Outlook double-spaces your signature

Classic Outlook for Windows doesn’t render HTML with a browser engine. It uses Microsoft Word’s rendering engine, and has since Outlook 2007. Word treats every <p> tag as a paragraph and applies its default paragraph spacing — roughly a blank line’s worth of space after each one.

So if your signature HTML looks like this, each line becomes its own paragraph and Outlook inserts spacing after every single one:

<!-- Before: renders double-spaced in Outlook -->
<p>Jane Doe</p>
<p>Product Manager, Acme Inc.</p>
<p>+1 555 0123 · jane@acme.com</p>

The same thing happens when you type a signature directly into Outlook’s signature editor: pressing Enter creates a new paragraph, and each paragraph gets Word’s spacing-after. The editor is essentially a small Word document.

Gmail, Apple Mail, and Outlook on the web use browser engines that render <p> margins more compactly (and respect CSS that removes them), which is why the same signature can look fine there and broken on a colleague’s Windows desktop.

Fix 1: Shift+Enter when editing inside Outlook

If you build or edit your signature in Outlook’s own editor (File → Options → Mail → Signatures in classic Outlook, or Settings → Accounts → Signatures in new Outlook), the fix takes ten seconds:

1. Click at the end of a double-spaced line.
2. Delete the break by pressing Delete (or select to the start of the next line and delete).
3. Press Shift+Enter instead of Enter.

Shift+Enter inserts a line break within the paragraph instead of starting a new paragraph, so no paragraph spacing is applied. Repeat for each line. In classic Outlook you can also select all the text and set paragraph spacing to 0 via the paragraph options, but Shift+Enter is the habit worth keeping because it survives later edits.

This works in classic Outlook, new Outlook, and Outlook on the web. If you’re not sure which Outlook you have, our classic Outlook guide and new Outlook guide show how to tell them apart and where the signature settings live in each.

Fix 2: Fix the HTML itself

If you maintain the signature as an HTML file — for example, the .htm files classic Outlook keeps in %APPDATA%\Microsoft\Signatures — fix the markup at the source. Two changes matter:

1. Replace <p> tags. Use <br> for a quick fix, or table rows for full layout control:

<!-- After: renders tight in Outlook -->
<table cellpadding="0" cellspacing="0" border="0" role="presentation">
  <tr>
    <td style="font-family:Arial,sans-serif; font-size:14px;
               mso-line-height-rule:exactly; line-height:20px;">
      Jane Doe<br>
      Product Manager, Acme Inc.<br>
      +1 555 0123 &middot; jane@acme.com
    </td>
  </tr>
</table>

2. Set mso-line-height-rule:exactly before every line-height. By default, Word treats your line-height as a minimum and will silently grow a line to fit the tallest thing on it — an emoji, a logo, a superscript. mso-line-height-rule:exactly tells Word to use exactly the value you set. The order matters: declare it immediately before the line-height it governs. Other clients ignore the mso- prefix entirely, so it’s safe everywhere.

One caveat from the field: with exactly in effect, an image taller than the line-height of its container gets cropped to that height in Outlook. Keep images in their own <td> with explicit width and height attributes rather than inline with text.

If you’d rather not hand-edit HTML

This entire class of bug is avoidable at generation time. The OnceSig editor builds every template as a table with inline styles, no <p> tags anywhere, and mso-line-height-rule:exactly paired with an explicit line-height on every line — so the spacing you see in the preview is the spacing Outlook renders. Images get explicit width/height attributes plus CSS dimensions, which also keeps them sharp on high-DPI displays.

The editor is free to use; exports carry a small credit line until a one-time license (from $9, no subscription — see pricing) unlocks clean export. Either way, you can copy the result as rich text or download an .htm file ready for classic Outlook’s Signatures folder, and the double-spacing problem never shows up in the first place.