Professional Email Signature UK Guide: What to Include, Legal Details and Design

A professional email signature in the UK should include your name, role, company, phone number and website. If you're a limited company, it should also carry the company's registered name, registered number, registered office address and the part of the UK where it's registered. Keep it short, mostly text, with a small logo that has alt text.

Most businesses get the look of their signature roughly right. Where they slip is the legal small print, which many UK companies leave out entirely, and the technical details that make a signature fall apart in Outlook or on a phone. This guide covers both, and you can build one in a couple of minutes with our free email signature generator.

What a professional email signature should include

Start with the essentials and resist the urge to add everything else.

Things to leave out: inspirational quotes, multiple phone numbers nobody uses, large banners, every social network, and long disclaimers that nobody reads (more on those below).

UK legal requirements for email signatures

Limited companies

The rules come from the Company, Limited Liability Partnership and Business (Names and Trading Disclosures) Regulations 2015, made under the Companies Act 2006.

Registered name on all business correspondence. Regulation 24 requires a company to show its registered name on its business letters and on "all other forms of its business correspondence and documentation." Regulation 29 says a reference to a type of document includes one "in hard copy, electronic or any other form." Business emails are therefore covered.

Further particulars on business letters, order forms and websites. Regulation 25 requires every company to show on its business letters, order forms and websites:

• the part of the United Kingdom where it's registered (England and Wales, Scotland, or Northern Ireland)
• its registered number
• its registered office address

GOV.UK's guidance for limited companies lists the same details. An email doing the job of a business letter, such as a quote, contract correspondence or an order, falls naturally within that, and because the regulations cover documents in electronic form, the practical and widely followed approach is to put all of these details in every business email signature. It costs one or two lines.

Directors' names are optional. Under regulation 26, if a business letter includes the name of any director (other than in the body text or as the person signing it), it must include the names of all the directors. Signing your own email as a director doesn't trigger this. Adding a "Directors:" line listing only some of them does.

Share capital is optional. If you do mention share capital, it must be the paid-up share capital.

VAT number. You don't need it in an email signature. It must appear on VAT invoices. Some businesses include it anyway.

Not complying is an offence for the company and its officers under the Companies Act 2006, enforced by Companies House and Trading Standards. In practice the fix is simple, so there's no reason to risk it.

A compliant footer looks something like this:

Acme Plumbing Ltd. Registered in England and Wales, company number 01234567.
Registered office: 1 Example Street, Leeds, LS1 1AA.

LLPs, sole traders and partnerships

Limited liability partnerships have equivalent disclosure rules under the same regulations. Sole traders and partnerships that trade under a name other than their own have separate requirements to show the owners' names and an address on business documents. Check GOV.UK for the rules that apply to your structure.

Do you need an email disclaimer?

Long confidentiality disclaimers ("This email and any attachments are confidential...") are common but aren't a legal requirement, and their legal effect on someone who receives an email by mistake is doubtful. If your regulator or insurer asks for specific wording, such as for solicitors, accountants or financial advisers, follow that. Otherwise, a short line is plenty. Our guide to email security for solicitors covers what actually protects you in regulated sectors.

Design that works in every email client

Email clients render HTML very differently. Outlook on Windows uses a Word-based rendering engine that ignores much modern CSS, Gmail strips some styles, and phones shrink everything. A signature that looks perfect in one client can break in another.

Layout

• Use simple tables, not CSS layouts. Tables are the most reliable way to position a logo next to text across clients. Our email signature generator builds table-based HTML for exactly this reason.
• Keep it narrow. A signature that's wider than a phone screen forces sideways scrolling.
• Keep it to a few lines. Name, title, company, contact line, legal line. A signature longer than the average reply looks odd in long threads.
• Use web-safe fonts such as Arial, Helvetica, Verdana or Georgia. Custom fonts often fall back to Times New Roman.
• Use inline styles for colours and fonts. Many clients ignore styles in the head.

Images and logos

Images cause most signature problems. A few rules:

• Expect images to be blocked. Many email clients and corporate setups don't load remote images until the reader allows them. Your signature must make sense without the logo.
• Keep the logo small. It should be a supporting element, roughly the height of your text block. Resize it to the size it will display, with a version at twice that for high-resolution screens, rather than uploading a large file and shrinking it in HTML. The image resizer helps, and compressing the file keeps it light.
• Set width and height in the HTML so the layout doesn't jump when the image loads, and so Outlook doesn't display it at full size.
• Host images on your website over HTTPS rather than attaching them. Embedded images often show up as attachments, which clutters threads and can look suspicious.
• Use PNG or JPG. SVG isn't supported in many email clients, and animated GIFs may only show their first frame in some versions of Outlook.
• Don't make the whole signature one image. It can't be read with images off, can't be read by screen readers, can't be copied, and adds weight.

Size and length

Keep the HTML lean. Signatures pasted from Word or a web page often carry lots of hidden code. Gmail rejects signatures that are too long, and very long HTML in emails can contribute to Gmail clipping messages behind a "View entire message" link. A generated signature with inline styles avoids most of this.

Accessibility

An accessible signature is also more robust, so these steps help everyone.

1. Use real text for your name, contact details and legal information, not an image.
2. Add alt text to the logo. Usually just the company name, such as alt="Acme Plumbing". For decorative icons with a text label next to them, use empty alt text so screen readers skip them.
3. Check colour contrast. Light grey text on white is common in signatures and hard to read. Our colour contrast checker guide explains the WCAG ratios.
4. Use a readable size. Avoid tiny text for the legal line; it still needs to be legible.
5. Make links descriptive. "Website" or the domain itself is clearer than "Click here".
6. Don't rely on colour or icons alone. Label phone and email details with text, such as "T:" and "E:", or the words themselves.

Signatures and deliverability

A signature rarely gets an email marked as spam on its own, but some habits don't help:

• Lots of images and links in a short email push the image-to-text ratio in the wrong direction.
• Links to other domains, such as URL shorteners or tracking links, can look suspicious. Link to your own domain.
• Attached images in every message add weight and clutter.

Far more important is authentication. If your domain's SPF, DKIM and DMARC records aren't set up, even a perfect signature won't keep you out of spam. Run the free email deliverability checker, and see why emails go to spam for the full picture. If you want your logo to appear next to your messages in Gmail, that's done with BIMI rather than the signature; see BIMI logos in Gmail.

Rolling out signatures across a team

Consistency matters as soon as you have more than a few people.

1. Create one template with the legal details built in, so nobody can forget them.
2. Build each person's version from that template with the generator, changing only name, title and phone.
3. Install it in each client. Paste the HTML into Outlook, Gmail or Apple Mail settings, and check the mobile apps too, as they often use a separate plain signature.
4. Test it. Send an email to a Gmail address, an Outlook address and a phone, with images on and off.
5. Review it once a year, or whenever your registered office, branding or phone numbers change.

For larger teams, Microsoft 365 and Google Workspace can add a central footer or signature through admin rules, which guarantees the legal line is present. Make It Flow can help automate onboarding steps like this; get in touch if new-starter setup takes too much of your time.

FAQ

Is an email signature a legal requirement in the UK?

The signature itself isn't required, but limited companies must show their registered name on all business correspondence, including emails. They must also show their registered number, registered office address and place of registration on business letters, order forms and websites. Putting all of these in the email signature is the simplest way to comply.

What must a limited company include in its emails?

At minimum, the company's full registered name, including "Limited" or "Ltd". The widely followed approach is also to include the registered number, the registered office address and the part of the UK where the company is registered, such as England and Wales. Directors' names are optional, but if you list any, you must list them all.

Do sole traders need anything in their email signature?

There's no Companies Act requirement for a company name or number, because a sole trader isn't a company. If you trade under a business name that isn't your own name, you must show your name and a business address on business documents. Check GOV.UK's guidance for sole traders for the details.

What size should an email signature logo be?

Keep it small, roughly the height of your name and contact lines, and save it at the size it will be displayed, plus a double-size version for sharp screens. Set the width and height in the HTML, compress the file, and always add alt text, because many clients block images by default.

Why does my email signature look wrong in Outlook?

Outlook on Windows uses a Word-based rendering engine that ignores many modern CSS features, such as flexible layouts, some padding rules and background images. Signatures built with simple HTML tables, inline styles and web-safe fonts display far more reliably. Also set explicit image dimensions so logos don't appear at full size.

Should I use an image as my whole email signature?

No. A signature saved as one image disappears when images are blocked, can't be read by screen readers, can't be clicked or copied, and adds weight to every email. Use real text for your details and keep images to a small logo with alt text.