Email signature generator › Tester

Email signature tester

Paste the HTML. You get a score out of 100 and, more usefully, every point you lost explained with the fix.

What it checks

Thirty-three checks, in four groups. Every one is a mechanical test on your markup, not an opinion — the same signature always produces the same score.

Rendering (the expensive failures)

Flexbox and grid, floats, <style> blocks, media queries, web fonts, scripts, fonts mail clients do not have, position, background images, SVG, and the worst case of all: a signature that is really just an image with text baked into it.

Structure

Whether the layout uses a table at all, whether the table carries the cellpadding, cellspacing and border attributes older clients need, border-collapse, margins on block elements, and classes that reference a stylesheet which will never arrive.

Images and links

Missing width and height, missing alt, the blue border Outlook draws on linked images, http images on an https page, data URIs, images hosted on Drive or Dropbox that will never load, too many images, links with no explicit colour, and a signature with no way to contact you at all.

Type and length

Font sizes in em, rem or pt, text under 10 px, missing font-family, total size over 5 KB, Gmail’s 10,000 character cap, more than six lines, and filler text like "sent from my" or a printing notice.

How the score works

You start at 100. Each failed check subtracts a fixed number of points according to how much damage it does: 14 for a signature that is one big image, 12 for flex layout, 3 for a missing border:0. Nothing is weighted by taste, and every deduction is shown with its cost next to it.

A high score is not a promise. It means your markup avoids every failure mode we know about, which is different from being tested in forty clients. The four-minute manual test — send to Gmail, open on a phone, turn images off, hit reply — is still worth doing.

Why a score and not just a list

Honestly: because a number tells you whether to care. A list of eleven findings with no weighting reads as eleven equal problems, and most people fix the easy three and leave the one that actually breaks the signature. The score puts the damage in order, and the "−12" beside a finding is the argument for doing that one first.

It is also why the number is never shown on its own. Every point lost is itemised, named, and linked to the page here that explains the underlying rule.

Where to get your signature HTML

This is the awkward part, because most signature boxes are visual editors with no code view. What works:

• Apple Mail: the signature is a file on disk — see where Apple Mail keeps signatures.
• Outlook for Windows: the .htm file in %APPDATA%\Microsoft\Signatures. Open it in a text editor and copy everything.
• Any client: send yourself a message, open it in a browser-based mail client, and use "show original" or the browser’s inspector to copy the signature markup.
• A signature somebody built for you: whoever supplied it has the HTML. It is worth asking, because agency-built signatures are the ones that most often fail these checks.

If none of that is practical, the faster route is to generate a clean signature and compare it against what you have.

Nothing leaves your browser

The parsing and the checks run in your browser with the standard HTML parser. There is no upload, no account, and nothing stored — which matters here more than on most tools, because a signature contains your name, your phone number and your employer.

Frequently asked questions