The 17 DOs and DON’Ts of email signatures

Get the basics of email signature design right

A well-designed email signature does its job quietly. It keeps contact details accurate, reinforces brand consistency, and doesn’t give your IT team another ticket to deal with.

But it’s easy to get wrong. Too much information, poor formatting, or mismatched styles across teams can cause more harm than good.

As an email signature management provider, we know a thing or two about email signature design. We know what many companies get right and what they get wrong.

This list covers 17 dos and don’ts that make a difference in email signature design, whether you’re managing a few dozen users or thousands. These are the basics that help keep your signatures clean, consistent, and under control.

1. Do connect email signature design to social media

Social media is part of your digital brand, so it should feature in your email signature. Add a LinkedIn Follow icon or link to current content—like a new blog or customer story.

Email signature design tools let you do this consistently, at scale. Unilever, for instance, added a LinkedIn “Follow” button to its corporate signature and grew its follower count from 40,000 to 235,000 in 10 months—without a paid campaign.

Don’t cram in every platform

Stick to one or two relevant channels. You don’t need to include icons for platforms your audience doesn’t use.

2. Don’t leave it to individuals

When every employee builds their own email signature, inconsistencies are guaranteed. You’ll see outdated logos, typos, mismatched formatting, and broken links across the board.

Centralize the design. Use a consistent, approved email signature template that reflects your brand and works across devices.

Do use one version for everyone

Whether you're a team of 20 or 2,000, consistent formatting signals professionalism and prevents support issues.

3. Do use purpose-built tools

Email signatures aren’t documents or webpages. If you try to build them in Word, Outlook, or a CMS, you’ll run into rendering issues.

If you know HTML, code your signature to match email standards. If you don’t, use an email signature management solution that does the heavy lifting for you.

Don’t assume Word is ‘good enough’

What looks fine in your email editor can fall apart in Gmail, Apple Mail, or mobile devices.

4. Do use a sensible email signature size 

Whether in Gmail, Outlook, or Apple Mail, very wide email signatures will not render well for a recipient. The industry standard for email signature size is about 650 pixels. We’d even say a signature design should be a little thinner at 600px. This ensures nothing gets lopped off the edge of a message. 

Need extra certainty? A slimmer layout—around 450px—reduces the risk of rendering issues across devices.

Don’t design without testing

Use tools that let you preview across clients. Signatures that break layout lose trust fast.

5. Do structure your layout with tables

Tables are the most reliable way to align elements in your email signature. They keep spacing consistent and prevent your logo or contact details from jumping out of place.

Make borders transparent so they don’t show. Tables aren’t stylish, but they work.

Don’t rely on divs or images to handle layout

Email clients don’t behave like browsers. Stick to what’s proven to render consistently.

6. Do make an email signature design simple 

Your email signature should be clean and functional. Let the content do the work. Over-designed layouts often break across email clients.

If you want to try something ambitious, test it thoroughly across Outlook, Gmail, and Apple Mail.

Don’t skip the basics

Include full contact details: full name, job title, company, phone number, and email address. If it’s on your business card, it should be in your signature.

7. Don’t use bullet points

Bullets don’t render consistently across email clients. Gmail and Outlook treat them differently, which often leads to misalignment or broken formatting.

Use rows within your table to create space and separation instead.

Do keep the format predictable

Stick with table-based spacing and line breaks. You’ll save yourself email signature formatting headaches later.

8. Don’t animate it unless you’ve tested it 

Animated GIFs or embedded videos often break in Outlook and other clients. If they don’t render, recipients may just see a broken link or blank space.

If you’re using animation, test it thoroughly and prepare a fallback. Otherwise, keep it static.

Do use static banners or icons when in doubt

Static designs display reliably, load faster, and work in every inbox.

9. Do make email signatures mobile-friendly 

Most emails are opened on mobile devices. Your email signature design needs to be responsive.

Break up contact details across multiple lines so they don’t wrap awkwardly. Test the mobile email signature on different screen sizes to confirm it fits without scrolling.

Don’t assume desktop-first will scale

What looks good on your monitor might break on a phone. Design for small screens from the start.

10. Do write full-length HTML 

Shortcuts, like WYSIWYG editors or pasted Word formatting, often fail in email environments. They rely on code that email clients may not understand.

If you’re coding your signature, write the email signature HTML by hand. If you’re not, use an email signature generator.

Don’t treat email like a web browser

Web rules don’t apply here. Build your email signature the way email clients expect.

11. Do use images in email signatures

Visual elements like logos and banners can reinforce your brand if they’re used correctly. Host the image on a reliable server and reference it via URL, or embed it if your email platform supports it.

Don’t assume the image will load

Always test image rendering. Broken visuals create a bad impression and make your signature look unprofessional.

12. Do hardcode image dimensions

Set the exact width and height of every image in your email signature. Without defined dimensions, email clients like Outlook may display the image incorrectly or distort its aspect ratio.

Don’t leave it up to chance

Unspecified image sizes can break layouts, cause alignment issues, or lead to blurry rendering. Use tools that allow you to control dimensions precisely.

13. Do balance images with text

An email signature should support the message, not overpower it. If you're sending a one-line email, a massive graphical signature will feel out of place.

Use a larger version for new conversations and a simplified version for replies or forwards.

Don’t let visuals dominate the layout

The signature should support communication, not compete with it.

14. Don’t skip alt text 

Alt text helps your content stay readable, even when images don’t load. It also improves accessibility and clarifies the function of each element.

Add short, clear descriptions that match the purpose of the image (e.g., “Follow us on LinkedIn” or “Register for our event”).

Do treat images as functional content

Alt text should explain what the user can do—not just what they’re looking at.

15. Do use email signatures for marketing purposes 

Every email you send is an opportunity to promote something relevant—whether it’s a product update, upcoming event, or a new piece of content.

Including email banners, CTAs, or campaign links in your signature keeps messaging consistent and visible without needing to send another email.

Don’t make it an afterthought

Use branded visuals and concise copy that match your campaign goals. Done right, an email signature is a low-effort, high-visibility way to support marketing without adding noise. 

16. Don’t ignore legal requirements

It’s not exciting, but email disclaimers are required in many parts of the world. 

From the Health Insurance Portability & Accountability Act (HIPAA) for U.S. healthcare organizations to the UK Companies Act stating all business emails must include certain business information, look into what laws apply to you and what’s needed to comply with them. 

Do keep legal copy small and separate

Disclaimers belong in the signature, not in the spotlight.

17. Don’t overcomplicate email signature design

Email signatures may be a massive asset, but they don’t need to be an enormous effort. There are many intelligent ways to add a personalized email signature design to all emails without bothering your IT department or colleagues. 

Using Exclaimer saves countless hours and guarantees that every user gets a consistent email signature when sending from any web-enabled device. 

Do make it easier on your team

Exclaimer handles the setup, management, and updates, so your IT team can focus on more strategic work.

Learn more about Exclaimer or get yourself a free trial to see the power of email signature software for yourself.