Email signature: what it is, what to put in it and how to set it up

An email signature is the block of text at the bottom of an email that says who you are and how to reach you. A good one takes a minute to read and answers the questions a stranger would otherwise have to email back to ask: who is this, what do they do, which company is it, and what number do I call.

This guide covers the whole subject in one place. It starts with what an email signature should contain, then size and design, then legal lines, then how to set one up in the mail app you use. At the end it covers the harder problem, which is getting a whole company to use the same one. Each section links to a longer article if you want the detail.

What an email signature is for

A signature does three jobs. It identifies the sender, it gives the recipient a way to respond that is not “reply to this email”, and it makes the message look like it came from a real organisation. The first two are practical. The third matters more than people admit: a client who has never met you reads the signature the way they would read a business card.

There is also a plainer reason. People forward emails. When your message reaches a third person, the signature is often the only thing that tells them who wrote it. A forwarded message with no sign-off becomes a puzzle.

If you want the definition and the history in short form, the article on what an email signature is covers it.

What to put in a business email signature

A professional email signature has a small core and a few optional extras. Start with the core.

1. Your full name. The name you use with clients, spelled the way you want it.
2. Your job title. Specific is better than clever. “Head of Partnerships” beats “Growth Ninja”.
3. Your company name. The name people will recognise, and the registered name if your company has to state it.
4. One direct way to reach you. Usually a phone number, in a format that works from abroad.
5. Your website. One link, to the page you most want people to see.

Then add the extras that earn their place:

• A company logo or a photo. One or the other is fine. A logo makes the email look official, a photo makes it personal.
• A booking link if people often need a call with you. It saves a round of “when are you free” emails.
• Social links, but only the networks you really use for work. Two icons are better than eight.
• A legal footer if your company needs to show a registration number, a regulator line or a confidentiality notice.

A professional email signature is mostly about restraint. Every line you add pushes the sentence you wrote further up the screen.

What to leave out

Quotes, long disclaimers nobody reads, animated images, banners for last year’s campaign, and a line about the environment asking people not to print the email. Each of them once seemed a good idea. None helps the reader. If your company legally needs a notice, keep it short and put it at the bottom in small, grey text.

Size and format

Two numbers matter: how wide the signature is and how heavy the images are.

For width, 600 pixels is a safe ceiling. It fits comfortably in a desktop reading pane and shrinks on a phone without breaking. Logos at 120 to 200 pixels wide are enough. Save them at twice that size so they look sharp on high-resolution screens, then set the displayed width in the signature.

For weight, keep each image small, in the tens of kilobytes. Heavy images slow the message down and can push a mobile email over the point where the app stops loading images automatically.

Gmail also limits the signature itself: it accepts up to 10,000 characters, images included, according to Google’s Gmail signature help page. The email signature size guide goes through the limits app by app.

Design rules that survive every inbox

An email signature is not a web page. Mail apps strip or ignore much of what a browser accepts, and they do it differently. Classic Outlook for Windows, for example, draws email with the layout engine from Word, which is why a design that looks right in Gmail can fall apart there.

The rules that hold up in practice:

• Use tables for layout. Floats, flexbox and grid are not reliable in email.
• Put styles inline. A stylesheet in the head of the message is often discarded.
• Host your images. Link to an image on your own site rather than pasting it into the message. Pasted images are often sent as attachments or as inline pictures that some apps show as a red cross.
• Use safe fonts. Arial, Helvetica, Georgia and the like. If the font you pick is not installed, the app substitutes one.
• Write alt text for images. Many apps block images until the reader allows them. Alt text means the company name still shows.
• Check dark mode. A dark logo on a transparent background disappears on a dark background. Use a version with a light outline, or a separate dark logo.

Here is a classic layout drawn by emailfooter, with a photo, contact lines and a logo. It is built from tables and inline styles, the kind of HTML mail apps keep intact.

A classic layout with photo, logo and contact lines. The company and person are made up.

Examples for different jobs

The right signature depends on the work. A few patterns:

• A consultant or freelancer wants a photo, a booking link and a short line about what they do.
• A law or accounting firm wants titles and credentials, the firm’s registration line and a confidentiality notice, all in a restrained layout.
• A sales team wants a direct mobile number and a booking link above everything else.
• A school or a clinic wants the office number first and a notice about privacy.

The industry pages go further into each: see email signatures for law firms, accounting firms, real estate agencies and schools. And the article on email signature templates shows several layouts side by side.

An executive layout with a confidentiality notice in the footer. The firm and person are made up.

Email signature etiquette

A few habits make an email signature work better in daily use.

• Match the signature to the message. A full signature on the first email, a shorter one on replies. Both Gmail and Outlook let you set one for each.
• Do not repeat yourself. If your title and company are in the signature, you do not need to type them again at the end of the message.
• Keep the tone of the signature neutral. A motivational quote reads fine to the person who chose it and oddly to a client at a bank.
• Use one phone number per purpose. An office line for the switchboard and a mobile for direct contact is plenty. A list of four numbers makes people guess which to use.
• Check it on a phone. Send yourself a test and open it on your phone. If you have to pinch and zoom, it is too wide.
• Review it twice a year. A change of title, number or address is easy to miss, and an old signature does the most harm in the emails that get forwarded the longest.

Legal lines and company details

Some companies have to show particular details in business communications. The rules differ by country, and in several places the law talks about business letters without saying whether emails count. Because of that, many companies put the same details in the signature anyway.

Two examples we looked into. In the United Kingdom, GOV.UK says a limited company must show its registered number, registered office address and place of registration on business letters, order forms and websites; our UK page covers it. In Nigeria, section 304 of the Companies and Allied Matters Act 2020 lists what business letters must show; see the Nigeria page. For other countries we only state a rule when we have read an official source, so some pages say nothing about law. Ask your lawyer or company secretary what applies to you.

The practical advice is the same everywhere. Write the legal line once, in a footer, and make it impossible for individuals to delete it. If it depends on each person to remember, it will be missing on some messages.

How to set up an email signature

The steps depend on the app, but the shape is always the same: open settings, find the signature section, paste or build the signature, choose when it is used, save.

• Gmail: open Settings, choose See all settings, find the Signature section on the General tab and create a new one. See how to add an email signature in Gmail.
• Outlook: in new Outlook and Outlook on the web, open Settings, then Accounts, then Signatures. Classic Outlook uses the Signatures button on the Message tab. See how to create an email signature in Outlook.
• Other apps: the general guide to setting up an email signature covers Apple Mail and others.

Phones are the usual gap. A signature built on the desktop does not appear in the Gmail or Outlook app on a phone unless you set it up there as well, and several apps accept only plain text in the mobile signature. If much of your email goes out from your phone, set it up there too, even if it is only your name, title and number.

Getting a whole company to use the same signature

Everything above is easy for one person and awkward for fifty. Without a system, each employee builds their own. The logo is a different size on every message, the phone number is in four formats, and when the company changes address, half the team never updates.

There are three ways to solve this.

1. A template in a document. Someone writes the HTML, emails it round, and everyone pastes it. It works until the first change.
2. A central tool that pushes signatures to every mailbox through your Google Workspace or Microsoft 365 admin. This is the most automatic option, and the tools that do it are paid, often per user.
3. A shared design that each person fills in. The company fixes the layout, logo, colours and legal line. Each employee adds their name, title and phone number and installs the result in their own mail app.

emailfooter is the third kind. It is a free WordPress plugin: the company admin sets the design once, employees edit only their own details, and each person gets numbered steps for their mail app. It does not push signatures into mailboxes for you, so people install their own. If you need automatic deployment, see our honest comparison with WiseStamp.

If you want to try it, the plugin page has the download, and emailfooter Managed is the same software hosted for you.

Common mistakes

• Pasting an image into the signature box instead of linking a hosted one.
• Using a phone number in local format, which cannot be dialled from another country.
• Making the logo so large that it pushes the message down the screen.
• Leaving the signature off replies, so only the first message carries it.
• Forgetting the phone. The desktop signature is fine and the phone sends “Sent from my iPhone”.
• Never updating it after a move, a rebrand or a change of number.

Frequently asked questions

Should every email have a signature?

Business email should. Both Gmail and Outlook let you choose whether a signature goes on new messages, on replies and forwards, or both. A shorter version on replies keeps long threads tidy.

How long should an email signature be?

Four to seven lines of text plus an optional logo is normal. If it takes more space than the message, shorten it.

Can I use an image as my whole signature?

It is a bad idea. Many apps block images by default, so the reader sees nothing, and screen readers cannot read it. Use real text, and use images only for the logo or photo.

What is the best size for a professional email signature?

About 600 pixels wide, with a logo of 120 to 200 pixels. Details are in the size guide.

Do I need a different signature for mobile?

You need one set up on mobile, because the desktop one does not follow you. It can be shorter.

Is a free email signature generator enough?

For one person, yes. For a company, a generator gives you a good-looking block of HTML and nothing to keep it consistent afterwards. That is the gap a shared design closes.