What a UK limited company must show in its emails under the Companies Act, what to leave out, a layout that survives Outlook and phones, and how to build and reuse the signature with the Digily Link signature builder.
An email signature is seen more often than any advert a small company will ever run, by the people most likely to buy, and it is usually put together in five minutes and never looked at again. It is also, for a limited company, a legal document. This guide covers what the law requires, what to leave out, a layout that does not fall apart in Outlook, and a way to build the signature once and hand it to the whole team.
What the law requires
Under the Companies Act 2006 and the Companies (Trading Disclosures) Regulations 2008, business emails count as business letters. A limited company, a PLC or an LLP must show on them:
- the registered company name, exactly as it appears at Companies House;
- the company registration number;
- the place of registration, for example "Registered in England and Wales" or "Registered in Scotland";
- the registered office address, which may differ from the trading address.
The rule applies to every business email sent to someone outside the company, including replies, and every member of staff who sends them. Failing to comply can lead to a fine, and it can also allow a customer to argue they did not know who they were dealing with. A VAT number is not required in emails, though it is required on VAT invoices. Sole traders and partnerships are outside these regulations, but a sole trader using a business name should still show their own name and an address for service.
The legal line goes at the bottom in small text, in one or two lines. Something like "Nook Coffee Ltd, registered in England and Wales, company number 12345678. Registered office 1 Example Street, Leeds LS1 1AA." is complete.
What to include, in order
- Your name, then your role.
- The company name, or the logo with the name as alt text.
- One phone number.
- One link. A bio link page is ideal here because it holds the website, the booking page, the social accounts and a vCard behind a single address, so the signature stays short.
- The legal line.
Five lines plus the legal line is enough. Everything else competes with the message you actually wrote.
What to leave out
- Inspirational quotes and taglines.
- A row of six social icons. One link to a page that lists them does the same job and works in every email client.
- Large images, banners and scanned handwritten signatures. Many clients block images by default, and the reader sees a broken box.
- Long confidentiality disclaimers. They carry little legal weight in the UK and push the legal line off the screen. If your sector expects one, keep it to a sentence.
- "Sent from my phone" apologies. Set up the same signature on the phone instead.
A layout that survives Outlook and phones
- Text, not a picture. A signature saved as one image cannot be copied, searched or read by screen readers, and it is blocked by default in many inboxes.
- Keep it narrow. Around 320 pixels wide reads well on a phone without wrapping. Most email is now opened on one.
- Web-safe fonts. Arial, Helvetica, Georgia or Verdana. A brand font that is not installed on the reader's device is replaced by something you did not choose.
- One small logo with alt text. Under 30 KB, on a transparent background so it works in dark mode. The image optimiser gets it there.
- Dark mode. Avoid pure white text and pure black backgrounds in the signature itself; let the email client set them.
- No attachments. A logo added as an attachment appears as a file on every email you send.
Build it once with the signature builder
The email signature builder in the Digily Link dashboard produces the signature from a template. Enter the name, role, phone number, logo, link and social icons, choose a theme, preview it, then copy the HTML or export it. The free plan includes five signatures, Starter 25 and Pro 50, which is enough to give each member of a team their own version of the same design. On the paid plans signatures can be assigned to projects, one per client if you are an agency.
Paste the HTML into the signature settings of Gmail, Outlook, Apple Mail or your phone's mail app. If you want a quick version without an account, the free signature generator tool builds a simple one in the browser.
Measure the link
A signature link is a marketing channel, so treat it like one. Make the link a short link, for example digily.uk/yourname, so it can be changed later without asking the whole team to update their signatures, and tag its destination with the UTM link generator using utm_source=signature and utm_medium=email. The statistics then show how many clicks the signature earns each month, which is often more than the social accounts combined.
If you meet people in person as well, a vCard QR code in the signature is worth considering, as described in the guide to vCard QR codes for business cards. Keep it small and remember that images may be blocked, so the text link must stand on its own.
Frequently asked questions
Do sole traders need the legal line?
The Companies Act rules apply to registered companies and LLPs. A sole trader trading under a business name should still give their own name and a business address, which is also good practice for trust.
Does it apply to internal emails and replies?
Internal emails, no. Replies to anyone outside the company, yes, because they are still business letters.
What about a Scottish or Northern Irish company?
Same rules, different wording. "Registered in Scotland" with the SC number, or "Registered in Northern Ireland" with the NI number.
Can the legal information be in a footer only on the first email?
No. Every business email needs it, which is why it belongs in the signature rather than typed by hand.
How do I give the whole team the same signature?
Build one design in the signature builder, duplicate it for each person with their name and number, and send each person their HTML. Changes to the company details are then a matter of updating the template and sending the new version once.
Final checks
- Registered name, number, place of registration and registered office are all present.
- The signature is text with one small logo, under 320 pixels wide.
- There is one link, and it is a short link you can change later.
- It looks right in Gmail, Outlook and on a phone, in light and dark mode.
- Everyone in the company is using the same version.
