10 Email Signature Mistakes That Make You Look Unprofessional

A client once told me they nearly didn't hire our agency. The reason? One team member's signature had a quote about "living life to the fullest" and another had Comic Sans. True story.

Your email signature is seen more than your website. More than your LinkedIn profile. If you send 50 emails a day, that's 250 impressions per week. And most signatures? They're quietly sabotaging the sender.

Here are the mistakes I see constantly - and how to fix them fast.

1. No Standardization Across Your Team

This one's brutal. Your sales rep has a different format than your CEO. Marketing uses the old logo. Support forgot to update their phone number three months ago.

The result? You look disorganized. Prospects notice inconsistency more than you'd think.

The fix: Create one template. Use it everywhere. If you've got more than five people, you need centralized management - not hope and Slack reminders.

2. Using Weird Fonts

Script fonts look personal. They also look unreadable to half your recipients. And if you pick a font that's not web-safe? It'll render as Times New Roman anyway.

Safe choices: Arial, Helvetica, Verdana, Georgia. Boring? Maybe. Professional? Definitely.

3. Information Overload

Name, title, company, phone, mobile, fax (yes, people still include fax), email, website, LinkedIn, Twitter, Instagram, TikTok, physical address, legal disclaimer, inspirational quote...

By the time someone finds your phone number, they've given up.

The fix: Five elements max. Name, title, company, one phone number, website. Everything else is optional noise.

4. Images Sent as Attachments

Ever noticed that little paperclip icon on emails that shouldn't have attachments? That's your signature images being sent as files instead of being properly hosted.

Some email clients block these entirely. Others show them as broken images. Neither looks great.

The fix: Host images on a web server and link to the URL in your HTML. Or use a tool that handles this automatically.

5. Designing the Entire Signature as One Image

I get it - designers want pixel-perfect control. So they export the whole signature as a PNG.

The problems:

• Recipients can't copy your contact info
• Phone numbers aren't clickable
• Spam filters get suspicious
• Screen readers can't parse it

The fix: Use HTML with inline CSS. Keep images for your logo and headshot only.

6. Outdated Information

Nothing says "we don't have our act together" like clicking a link that 404s. Or calling a number that's disconnected. Or emailing someone who left the company eight months ago.

The fix: Quarterly audits. Seriously. Put it in your calendar.

7. Missing Legal Disclaimers

In the EU, you're legally required to include company registration information in business emails. In the US, certain industries have disclosure requirements. Skip these, and you're looking at fines.

This isn't optional for many companies. It's the law.

The fix: Check your jurisdiction's requirements. Add the minimum necessary text. Keep it small but present.

8. Too Many Colors and Sizes

Multiple fonts. Three different text sizes. Brand colors, personal colors, and that one shade of blue someone thought looked "modern."

Chaotic signatures suggest chaotic companies.

The fix: One font family. Two sizes maximum (name slightly larger than details). Two colors max - one for text, one for accent.

9. Including Personal Quotes

"Work hard, play hard." "Be the change you want to see." "I'll sleep when I'm dead."

In a professional context? These range from eye-roll to actively off-putting. Your signature isn't your Instagram bio.

The fix: Remove it. If you absolutely need personality, let your headshot and a clean design do the talking.

10. Not Testing Across Devices

Your signature looks perfect in Gmail on your MacBook. But 60% of emails are opened on mobile. And half your clients use Outlook.

What they see might be very different from what you designed.

The fix: Send test emails to yourself on different devices and clients. Check mobile specifically - it's probably where the problems are.

Frequently Asked Questions

What's the ideal length for an email signature?

Keep it to 4-7 lines of content. Include your name, title, company, and one or two contact methods. If recipients have to scroll past your signature, it's too long.

Should I include my photo in my email signature?

A professional headshot can increase response rates and build trust, especially in sales and client-facing roles. Just make sure it's properly sized (around 80x80 pixels) and professionally taken.

How often should I update my email signature?

Review quarterly for accuracy. Update immediately when job titles change, phone numbers change, or branding updates happen. Outdated signatures damage credibility.

Do email signatures affect deliverability?

Yes. Overly complex signatures with multiple images, external links, and heavy HTML can trigger spam filters. Keep it simple and well-coded for best deliverability.

Should every employee have the same signature?

For brand consistency, yes - with role-appropriate variations. A template system lets you maintain standards while allowing for different titles, departments, and contact info.

Key Takeaways

• Consistency across your team matters more than individual creativity
• Simple signatures outperform complex ones
• Web-safe fonts prevent display issues
• Host images properly to avoid attachment problems
• Test on mobile - that's where most people read email
• Legal disclaimers aren't optional in many jurisdictions
• Quarterly audits prevent embarrassing outdated info

What Now?

If you recognized your signature in any of these mistakes, you're not alone. Most companies get at least three of these wrong.

The good news: fixing them takes minutes. The bad news: without a system, the problems creep back.

We built Signkit's signature templates specifically to avoid these issues. One template, consistent deployment, and you never have to think about signatures again.

Or if you want to DIY it, just run through this list and fix what you find. Your future self (and your clients) will thank you.