10 email signature mistakes that make a company look careless

Email signature mistakes are rarely dramatic. They are small things, such as a picture where text should be, a link that goes nowhere or a number nobody can dial, and the reader notices them before they notice your message. Here are ten, each shown as what the reader sees, the before and after, and a one-line fix.

The vendor facts come from Google’s Gmail help page and Microsoft’s Outlook signature page, plus two Microsoft pages and two W3C pages linked below, all read in October 2026. The scenes are made up. Where a point is our own opinion, we say so.

Email signature mistakes in the content

1. The whole signature is one picture

Before: a single PNG holding the name, title and number. A reader whose mail app has blocked pictures sees a gap or a placeholder. Nobody can copy the number or tap it.

After: real text for the facts, with the logo as a small extra. Microsoft says classic Outlook blocks automatic picture downloads by default, and that the plain text format does not support showing pictures inside the message (picture downloads, message formats).

Fix: put your name, title and number in text, always.

2. There is no number, or it cannot be dialled

Before: a signature with a name, a title and an email address, so the reader must write back to ask for a number. Or the number is in local form, “0803 000 0000”, which does not work from another country.

After: “+234 803 000 0000”, one number, in the form that works from anywhere. See the phone number in email signature guide for which number to show.

Fix: one direct number, with plus sign and country code.

3. The title is out of date, or copied from someone else

Before: a promoted employee still signs as “Sales Executive” because the signature was copied from a colleague. Or a departed manager’s mobile number sits in a five-month-old thread.

After: one owner for each person’s details, and a check when roles change. Our guide to wording a job title covers the words.

Fix: keep details in one record and rebuild the signature from it.

Email signature mistakes in the build

4. An oversized image

Before: a 1,600-pixel logo squeezed to 150 pixels by the layout. The file is heavy, and in Gmail the image counts toward the limit: Google says you can put up to 10,000 characters in a signature and that your image also counts toward it.

After: a logo saved at about twice its display width and shown at 150 pixels. Our signature size guide has the numbers, and the signature too big article covers a fix step by step.

Fix: size the file to the display, not the other way round.

5. Pale, small text

Before: 11-pixel text in #9ca3af on white, a contrast ratio of about 2.5 to 1 by the WCAG formula.

After: 13-pixel text in #4b5563 on white, about 7.6 to 1. The W3C’s contrast criterion asks for at least 4.5 to 1 for ordinary text. It is a web accessibility standard, not a mail rule, but it is a fair test of whether people can read your small print.

Fix: measure the contrast, and make the smallest text the darkest.

6. Five fonts and four colours

Before: the name in one typeface, the title in another, the company in a third, and a different colour for each link. It looks assembled from leftovers.

After: one font family, one accent colour, and two sizes. This one is our rule of thumb, not a vendor limit, but a shared design makes it automatic. See email signature design for a spec.

Fix: one font, one accent, two sizes.

Email signature mistakes with links

7. A link that is broken

Before: the website link points to a page that was renamed last spring, or an address typed with one letter wrong. The reader clicks and sees an error.

After: every link opened once, after you build the signature and again whenever the site changes. Check the phone link on a phone and the email link in a mail app.

Fix: click every link in a message you send to yourself.

8. “Click here” as link text

Before: “Click here to book a call”. Out of context, it says nothing about where it goes.

After: “Book a 20-minute call”. The W3C’s link purpose criterion says the purpose of each link should be clear from its text or its context.

Fix: name the destination in the link itself.

Email signature mistakes in the setup

9. The signature exists on one device only

Before: a polished signature on the office computer and nothing on the phone, so half your messages go out bare. Microsoft’s page says signatures in classic Outlook can be stored on the device where they were made and may not be available on another.

After: a signature set up in each place you send from, and a shorter one for the phone. Gmail’s page says you can choose a signature default for new emails and for emails you reply to.

Fix: list the places you send from and set each one.

10. Testing in the wrong place

Before: you save the signature, look at the compose window and call it done. Microsoft’s page says classic Outlook does not add your new signature to the message you opened to create it. The window you looked at never had the signature.

After: a fresh message sent to yourself, then opened on a phone and in a second mail app.

Fix: judge a signature by what arrives, not by what you wrote.

A five-minute audit for email signature mistakes

1. Send yourself a message from every place you send from.
2. Open it on a phone and on a second app, ideally with images off.
3. Check that the name, title and number are readable without any picture.
4. Click each link, and tap the number on the phone.
5. Read it once as a stranger: could you tell who this is and what to do next?

If a step fails, the matching mistake above names the fix.

The same signature, corrected

This version applies the fixes: facts as text, one international number, readable colours, one font, link text that names the destination, and a short footer.

Corrected version: text for every fact, one number in international form, dark text on white, a booking link that names its purpose. The company and person are made up.

Keeping email signature mistakes from coming back

Ten checks are easy for one person and unreliable for fifty. The cause of most email signature mistakes in a company is that each person builds their own. A shared design fixes the build mistakes (4, 5, 6) in one place, and a single record per person fixes the content ones (2, 3). With emailfooter the admin sets the design and each employee fills in their own details. Employees still install the signature in their mail app by following the steps shown, because emailfooter does not push signatures into mailboxes, so the setup mistakes (9, 10) still need the audit above.

For the positive version of this list, read the best practices article, and for manners, see signature etiquette.

Frequently asked questions

What are the most common email signature mistakes?

A picture in place of text, a missing or local-format phone number, an out-of-date title, an oversized image, pale small text, a broken link and a signature that exists on only one device.

What makes a bad email signature?

Anything that makes the reader work. That means a long block, several fonts, banners for old campaigns, quotes, and facts that only appear inside an image.

How do I check my email signature for errors?

Send a fresh message to yourself, open it on a phone and a second mail app, and click every link. The audit above takes five minutes.

Why does my email signature look different on another device?

The other device may have no signature set up at all. Microsoft says classic Outlook can store signatures on the device where they were created.

Can email signature mistakes affect how professional my business looks?

They can, because the signature is the part of the message that carries your company’s details. A clean, accurate one signals care, and a broken one signals the opposite.