Email signature generator that does not break in Outlook

Who this page is for: anyone who has to build their own signature, or standardize one across a whole team, and would rather not find out later that it collapses for half of the recipients. If what you want is campaign parameters on a single link, and not the whole signature, go straight to the utm builder. If your question is about testing subject lines rather than the footer of the message, the path is the email A/B test sample size calculator. The three tools look at different parts of the same send: one builds the measured link, one sizes the test, and this one builds the block that travels at the end of every message.

The signature is the only ad you run every day for free

Someone who works over email sends somewhere between 30 and 40 messages per working day. On a ten person team that is close to 7,000 impressions a month of a block almost nobody designs on purpose, nobody measures, and that was usually copied from someone who had already copied it from someone else. No other space inside a company has that volume at that cost.

Two things tend to be wrong in that block at the same time. The first is technical: it was built with web page HTML and it collapses in Outlook. The second is measurement: the links carry no parameters, so every click leaving it shows up in the report as direct traffic, and the inevitable conclusion is that the signature drives no visits, when the truth is nobody ever knew.

This tool fixes both in the same step, and shows the result as numbers instead of promising it.

How to use it

1. Fill in name, job title and company. The preview redraws on every keystroke and already starts with a working example.
2. Adjust the contacts. The email becomes a mailto link, and a phone with the country code becomes a tap to call link on mobile, which is the difference between someone calling and someone copying the number by hand.
3. Point the logo at a public file on https and write the alt text. Email clients do not load local or insecure images, and half of them block images by default.
4. Pick the template and the accent color. The contrast of that color on white is measured beside it, because a pale green link on white is invisible on a phone screen in sunlight.
5. Leave utm tagging on and click copy the ready signature. Paste it into Gmail, Outlook or Apple Mail. If your IT team asks for the code, use copy HTML.

How it works: the four rules behind the output

There is no magic here. The block comes out of four decisions, all of them visible in the result:

The score is the sum of 12 checks with fixed weights, 100 points in total: name (10), job title and company (10), clickable email (10), clickable phone (8), website on absolute https (10), safe images (10), block weight (12), legal notice size (6), contrast (8), tagged links (6), lean signature (5) and call to action (5). Weight is the only check with partial credit: under 8 KB it pays in full, between 8 and 25 KB it pays half, above that it pays nothing.

One decision deserves an explanation: a signature with no image at all loses no points. It is the lightest one and the one that never breaks, and treating it as a mistake would push everyone toward a logo. What loses points is having an image that sits on http, runs too wide or has no alt text, because that is what actually breaks.

Worked example (reproduces the default output)

The example already loaded is the signature of a growth lead at a fictional company, with a 140 pixel logo, two social links and a booking button. Checking what the tool shows, number by number:

• Score: 95, band A, with one warning in the list.
• Block weight: 2.3 kB, well under the 8 KB of the full band and a comfortable distance from the 102 KB Gmail clip.
• Text lines: 7, against a limit of 6. That is exactly the warning: the street address is the seventh block.
• Clickable links: 6. Email, phone, website, LinkedIn, Instagram and the button.
• Contrast: 6.49:1, above the 4.5:1 WCAG minimum for small text.

The warning in the default is deliberate. The example signature is realistic, and a realistic signature is already over the line: it is the check most people fail, so it shows up immediately instead of hiding behind a rare case. Clear the address field and watch it close: lines drop to 6, the warning disappears and the score goes to 100.

Now run four more tests, each isolating a break that only shows up once the signature is already circulating:

• Turn utm tagging off. The score drops from 95 to 89 and the weight falls to 2.0 kB, because the parameters leave the five links. Lighter and blind: that is the trade almost every signature makes without noticing.
• Raise the logo width to 260. The score drops to 85, with the warning that past 200 pixels it pushes the text down on mobile.
• Change the accent color to #7fd0b0. Contrast collapses from 6.49:1 to 1.82:1, the score drops to 87 and the readability warning appears. The color still looks good on a desktop screen, and that is precisely the problem.
• Swap the logo https for http. The score drops to 85 and the image stops loading in email clients, which is a silent failure: in your own browser it still shows up.

The reference numbers

These are the values the tool uses. Some are published rules, others are market practice, and the difference matters when you have to argue the point with someone:

• 102 KB: the point where Gmail clips the message and hides the rest behind the view entire message link. Platform limit, not an estimate.
• 4.5:1: minimum contrast for small text against the background, per WCAG 2.1 level AA. Also a published rule.
• 8 KB and 25 KB: the signature weight bands. Our own criterion, calibrated on how repetition adds up in a long thread, not an official number from anyone.
• 200 pixel logo and 120 pixel photo: market practice, sized for the usable width of a phone in portrait.
• 300 characters of legal notice and 6 text lines: also our criterion, and the two most arguable on the list. They exist so you decide with a number in front of you instead of by eye.

How to read each number

The score measures what is under your control: the signature is complete, clickable, light and survives Outlook. It does not promise that every email client will render the block pixel for pixel, because that depends on rendering engines nobody controls, and any tool promising that is selling something that does not exist.

The block weight is the most underrated number on the list. It looks irrelevant at 2.3 kB, and it is, in one message. The problem shows up when you multiply it by ten replies in the same thread and add the signature of whoever is answering from the other side. That is why the full band is so tight.

The text lines count blocks, not visual lines. That is on purpose: the same signature takes three lines on a desktop and seven on a phone, and counting what you see on screen would give a different number per device. Counting blocks gives the same number everywhere and matches what you actually decide.

The contrast uses a white background because that is the email body background in practically every client. In dark mode the math changes, and the caveat follows: a very light or very dark accent suffers in one of the two modes, and the middle ground is what survives both.

Known limits

The biggest limit is that no tool can predict the behavior of every email client. Outlook 2016, Outlook for Mac, Outlook on the web and the new Outlook are four different renderers sharing one name, and that is before you add Gmail in the app and in the browser, Apple Mail, Thunderbird, Superhuman and the corporate clients. A table with inline styles is the common denominator that survives all of them, which is why it is the only output offered here, but a common denominator is not a pixel guarantee.

The tool also does not host your image. It takes the file address and checks whether it is absolute and secure, and that is everything you can do with no server in the middle. If the file sits behind a login, in a private folder or on a domain that blocks outside access, the signature will look right in your browser and arrive as an empty box in someone else's inbox. It is worth sending a test email to an account of yours on another provider before rolling it out to the team.

And the score is not a deliverability test. It looks at the structure of the block, not at your domain reputation, your sending authentication or your list history. A signature scoring 100 on an unauthenticated domain still lands in spam.

From a finished signature to a measured click

Once the block is assembled and tagged, the next question is what happens to the people who click:

• To build campaign parameters for any other link, and keep the team consistent, use the utm builder.
• If the signature button leads to a landing page, run it through the landing page grader before fighting for more clicks to a page that does not convert.
• To test subject lines with your list, see how many subscribers per version the test needs in the email A/B test sample size calculator.
• With a test running, check the verdict in the statistical significance calculator instead of calling it on the first good day.

FAQ

Why does my signature fall apart in Outlook?

Because Outlook for Windows does not render email with a browser engine: it uses the Word layout engine. In practice that means float, flexbox, grid, position and most of margin are ignored, and the block that looked perfect in Gmail collapses there. Most free generators hand you divs with flexbox, because that is how you write for the web, and the result is a signature that works for half of your recipients. The output here is a table with inline styles, the only layout Word, Gmail and Apple Mail draw the same way. There is deliberately no div option in this tool: offering the option would be offering the bug.

How do I put this signature into Gmail?

Click copy the ready signature, open Gmail settings, go to signature and paste with Ctrl+V. The button copies the block as formatted HTML rather than as code, so what lands there is the assembled signature and not a wall of tags. If your browser blocks the rich copy, the tool falls back to the selected preview on its own, which works the same way. In desktop Outlook the path is file, options, mail, signatures, and there too you paste. For tools that ask for the code, such as some corporate accounts and IT managed signatures, use copy HTML and hand over the text.

Do I really need utm tags on signature links?

You do if you want to know whether it works. With no campaign parameters, every click leaving your signature arrives in the report as direct traffic, mixed in with people who typed the address by hand. With utm, the signature becomes a measurable channel, and you find out something almost nobody measures: how many visits a month come from a team that only answered email. It is the cheapest tagging there is, because the send volume is happening anyway. If you need parameters for other campaigns, the utm builder handles the rest.

Does a logo in the signature hurt deliverability?

A small image hosted on https does not. What hurts is the extreme: a signature that is one big image with no text raises the odds a filter treats the message as promotional, because there is no content left to analyze. And a heavy file slows rendering on a bad connection. The practical rule is simple: real text on the contact lines, logo as a complement, width under 200 pixels, file on https and with alt text filled in, because half of email clients block images by default and without alt people see a blank rectangle where your brand should be.

What is the Gmail clip and what does my signature have to do with it?

Gmail stops showing a message past roughly 102 KB and hides the rest behind a view entire message link. A signature on its own rarely gets close to that, but it does not travel alone: in a ten reply thread the same signature shows up ten times, and it is the sum that blows the budget. That is why the tool shows the block weight instead of hiding it. Under 8 KB you are safe in any conversation; over 25 KB the signature is already the heaviest part of a long thread.

Should I include the confidentiality disclaimer?

That depends on your industry and your legal team, and that part is not a marketing decision. What is a marketing decision is the length. The notice repeats in every reply of the thread, so a three paragraph text becomes more content than the whole conversation after a few exchanges. The tool treats up to 300 characters as reasonable and warns above that. If your legal team requires a long text, a common way out is keeping one short sentence in the signature that points to a page with the full version.

Why does the tool complain past 6 lines?

Because the signature competes with the message. On a two line reply, a nine line signature becomes most of the screen, and the effect is the opposite of the intended one: instead of reinforcing the brand, it pushes the content up and out of the attention span. Six blocks of text already cover name, job title and company, contacts, website, social and a call to action. Full street address, a second phone number, awards and taglines are what usually goes over. The count is per block, not per visual line, so the same number holds at any screen width.

Does the tool store or send my data?

No. Everything runs in your browser: the fields never leave this page, no URL is fetched, nothing is stored and there is no server of ours in the middle. You can confirm it by opening the network tab while you type. That matters more here than in the average tool, because a signature carries the full name, phone number and work email of a real person, which is exactly the kind of data that should not travel through a free site server just to become a block of HTML.

Keep reading

To go beyond the footer of the message, continue with the complete guide to A/B testing in email marketing, see how to pick the send time and read about A/B testing email subject lines.