Short answer: A professional email signature is the short block at the end of your emails with your name, role, business, one phone number, your email address and your website. In Gmail, add it under Settings, See all settings, Signature, and make it the default for new emails and replies. Gmail takes images up to 100 pixels high.
What a professional email signature includes
Gmail describes a signature as text, like your contact information, that’s added at the end of your messages as a footer. Microsoft adds that it puts your contact information in every message and can carry links and images, such as a logo.
For a business, a short signature does the job: your name, your role, the business, one phone number, your email address, your website and a link to your main action, such as booking a call. A small photo or logo is optional.
Where each email app keeps your signature
| Email app | Where to create it | Good to know |
|---|---|---|
| Gmail on a computer | Settings, See all settings, Signature | One default for new emails and another for replies |
| Gmail app on Android | Menu, Settings, your account, Mobile signature | Without one, new messages use your computer signature |
| Gmail app on iPhone | Menu, Settings, Signature settings, Mobile Signature | Turn it on for each account in the app |
| New Outlook and Outlook on the web | Settings, Accounts, Signatures | Checkboxes add it to new messages and to replies and forwards |
| Classic Outlook for Windows | New message, Signature, Signatures | Saved on that device, so it may be missing on another one |
| Apple Mail on a Mac | Mail, Settings, Signatures | Drag an image into the preview to add it |
From Gmail Help, Microsoft Support and Apple Support, read November 3, 2026. Apple Mail places the signature above the quoted text in replies unless you clear that checkbox.
How to add a signature in Gmail
- Open Gmail on a computer, click Settings at the top right, then See all settings.
- In the Signature section, add your signature text in the box.
- Type your name, role, business, phone number and website, one per line.
- To add a logo or photo, enter a public web address, pick a public image from your Google Drive or upload a file.
- Keep the image 70 to 100 pixels high. Gmail’s maximum is 100 pixels high by 1,000 pixels wide.
- Choose your defaults for new emails and for replies. If you send from other addresses with Send mail as, give each one its own signature.
- Click Save Changes at the bottom of the page, then send yourself an email to check it.
Google ends Send mail as for addresses from other email providers in January 2027. Google Workspace aliases and other Gmail addresses you own keep working.
In new Outlook and Outlook on the web, open Settings, then Accounts and Signatures. Select Add signature, give it a name, type and format it, choose with the checkboxes where it goes and select Save. For a layout with tables or borders, Microsoft suggests creating it in Word and pasting it into the signature box of classic Outlook.
If you send marketing emails, our CAN-SPAM guide covers what US law asks for in each one. Our brand guidelines guide helps you keep the same logo and colors in your signature as everywhere else.
When the signature image doesn’t show
An image from Google Drive must be shared publicly, and it disappears from your signature if you delete the file. An image that’s too large can also break how the signature looks.
If you can’t find your signature in a sent message, Gmail may have hidden it under the message: scroll down and click Show trimmed content.
The signatures we use
Our founders’ signatures carry a name, the role and business, one phone number, one email address, the website and a link to book a call. Each one ends with our logo and starts with a small round photo.
We built them with tables, inline styles, system fonts and text at 13 or 16 pixels. They sat on a small web page with a copy button, and we pasted them into Gmail’s signature box. The photo shows at 64 pixels from a 192-pixel file, and the logo at 132 by 42 from a 352 by 112 file. Both show under Gmail’s 100-pixel height limit.
Both images live at public addresses on our website and carry alt text. Before we installed the signatures on October 5, 2026, we checked them in a real Gmail inbox, where both images loaded, and in dark mode. We haven’t tested them in Outlook.
Each of our addresses that sends through Gmail with Send mail as has a default signature assigned.
Before you call your signature done
- Your name, role and business come first.
- There’s one phone number and one email address.
- Your website and your main action have a link.
- Any image is under 100 pixels high and at a public address.
- New emails and replies have a default signature.
- You sent yourself a test and opened it on your phone.
RememberKeep the signature short, host the images at a public address, and set it as the default for new emails and replies.
If you want a signature that matches the rest of your brand, see our branding service.
Quick answers about email signatures
What should a professional email signature include?
Your name, your role, your business, one phone number, your email address and your website. Add a link to your main action, such as booking a call, and a small logo or photo if you want one. Leave out anything you wouldn’t want at the end of every email.
How do I add a signature in Gmail?
On a computer, open Gmail, click Settings and then See all settings. In the Signature section, type your signature, add an image if you want and click Save Changes at the bottom. You can also set defaults for new emails and replies.
What size should an email signature image be?
Gmail recommends an image 70 to 100 pixels high and 300 to 400 pixels wide. The maximum is 100 pixels high by 1,000 pixels wide, and the image also counts toward the 10,000 characters a signature can hold.
Why doesn’t my Gmail signature image show?
If the image comes from Google Drive, its sharing must be public, and it stops showing if you delete the file. Gmail also suggests deleting the image and adding it again, or trying another method: a web address, Drive or an upload.
Can I have more than one email signature?
Yes. Gmail lets you keep several signatures, set one default for new emails and another for replies, and pick a different one in each email. Outlook also lets you create several and choose one while you write.
Sources
Read on November 3, 2026. Gmail Help: Create a Gmail signature (computer, Android and iPhone) and Troubleshoot issues with Gmail signatures. Also from Gmail Help: Send emails from a different address or alias. Microsoft Support: How to add and change an email signature in Outlook. Apple Support: Edit text and email signatures in Mail on Mac. Our own case: our founders’ email signatures and their tests, October 2026.