How to Add Testimonials to Your Email Signature (Gmail, Outlook, Apple Mail)

Adding a testimonial to your email signature takes 5 minutes. But doing it wrong can make you look unprofessional.

Here's how to set it up correctly in Gmail, Outlook, Apple Mail, and other popular clients—plus formatting tips that work across all platforms.

Before You Start: Prepare Your Testimonial

Choose the Right Quote

Your signature testimonial should be:

• Short: Under 20 words (ideally under 15)
• Specific: Includes a result, number, or clear benefit
• Attributed: Real name, title, and company

Good example:

"Doubled our response rate in 2 weeks." — Sarah Chen, Founder at LaunchPad

Bad example:

"Great service, highly recommend!" — John D.

Format Template

Use this structure:

---
"[Your testimonial quote]"
— [Name], [Title] at [Company]

The horizontal line separates the testimonial from your contact info.

Gmail Setup

Desktop (Gmail Web)

1. Click the gear icon (top right) → See all settings
2. Stay on the General tab
3. Scroll down to Signature
4. Click + Create new or select your existing signature
5. Add your testimonial below your contact info:

Best regards,
[Your Name]
[Your Title] | [Company]
[Phone] | [Email]
[Website]

"Doubled our response rate in 2 weeks."
— Sarah Chen, Founder at LaunchPad

6. Click Save Changes at the bottom

Gmail Mobile App

Gmail mobile uses your desktop signature by default. To set a mobile-specific signature:

1. Open Gmail app → tap hamburger menu (☰)
2. Scroll down → Settings
3. Select your account
4. Tap Mobile Signature
5. Add a shorter version (mobile signatures should be minimal)

Mobile-friendly format:

[Your Name] | [Company]
"Doubled our response rate." — Sarah Chen, LaunchPad

Outlook Setup

Outlook Desktop (Windows)

1. Click File → Options → Mail
2. Click Signatures...
3. Select your signature or click New
4. Add your testimonial in the editor:

[Your signature content]

"Saved us 10 hours a week on reporting."
— Marcus Webb, Operations Lead at ScaleUp

5. Click OK to save

Outlook Desktop (Mac)

1. Click Outlook → Preferences → Signatures
2. Click + to add or select existing
3. Add your testimonial in the editor
4. Close to save

Outlook Web (Office 365)

1. Click gear icon → View all Outlook settings
2. Go to Mail → Compose and reply
3. Scroll to Email signature
4. Add your testimonial
5. Click Save

Outlook Mobile

1. Open Outlook app → tap profile icon
2. Tap gear icon (Settings)
3. Tap your account under Mail accounts
4. Tap Signature
5. Add your testimonial
6. Tap checkmark to save

Apple Mail Setup

Apple Mail (Mac)

1. Open Mail → Mail menu → Preferences (or Settings on newer macOS)
2. Click Signatures tab
3. Select your account in the left column
4. Click + to add or select existing
5. Edit in the right panel:

[Your Name]
[Title] | [Company]
[Phone] | [Website]

"The only tool I recommend to my clients."
— Priya Patel, Marketing Consultant

6. Close to save

iPhone/iPad Mail

1. Open Settings → Mail
2. Tap Signature
3. Choose Per Account or All Accounts
4. Add your testimonial

Note: iOS Mail has limited formatting. Keep it simple:

[Name] | [Company]
"Best investment this year." — Client Name

Other Email Clients

HubSpot

1. Click profile icon → Profile & Preferences
2. Go to Email tab
3. Edit your signature
4. Add testimonial in the HTML editor
5. Save

Superhuman

1. Press Cmd+K → type "signature"
2. Edit your signature
3. Add testimonial
4. Save

Spark

1. Open Spark → Preferences → Signatures
2. Select or create signature
3. Add testimonial
4. Close to save

Mailchimp (Transactional)

If using Mailchimp for transactional emails:

1. Go to Templates
2. Edit your email template footer
3. Add testimonial to the signature block

Formatting Best Practices

Do's

Don'ts

Mobile Optimization Checklist

Before going live, send yourself a test email and check on your phone:

• Does the testimonial display on one screen (no scrolling)?
• Is the text readable without zooming?
• Does the formatting survive (line breaks, dashes)?
• Is the attribution visible?
• Does any linked text work?

Pro tip: If your signature looks cluttered on mobile, create a shorter mobile-only version.

Troubleshooting Common Issues

"My testimonial doesn't show up"

Cause: Signature not set as default for new emails
Fix: In signature settings, set your signature as the default for "New emails" and "Replies/forwards"

"The formatting breaks on mobile"

Cause: Using HTML formatting that doesn't translate
Fix: Stick to plain text with simple line breaks

"The quote looks cramped"

Cause: No visual separator
Fix: Add a horizontal line (---) or extra line break before the testimonial

"Recipients see raw HTML"

Cause: Email client rendering plain text version
Fix: Use plain text formatting (no bold, no links in the testimonial itself)

"My signature is too long"

Cause: Including too much information
Fix: Move secondary info (social links, disclaimers) above the testimonial, or remove them

Templates by Email Client

Gmail Template

Best regards,
[Your Name]
[Title] | [Company]
[Phone] | [Website]

"[Your testimonial]"
— [Name], [Title] at [Company]

Outlook Template

[Your Name]
[Title]
[Company]
[Phone] | [Email]

"[Your testimonial]"
— [Name], [Company]

Apple Mail Template

[Your Name]
[Title] | [Company]
[Phone] | [Website]

"[Your testimonial]"
— [Name], [Title]

Mobile-Optimized Template

[Your Name] | [Company]
"[Short testimonial]" — [Name]

Next Steps

Once your signature is set up:

1. Send yourself a test email and check formatting
2. View on mobile to ensure readability
3. Set a reminder to rotate the testimonial quarterly
4. Track responses to see if engagement improves

Related Resources

• Email Signature Testimonials Guide — Strategy for choosing the right testimonial
• Email Signature Testimonial Examples — 25+ templates to copy
• How to Ask for Testimonials — Get the quotes you need

Use our free Email Signature Generator with Testimonial to create a professional signature with built-in social proof.

Start collecting Testimonials with Say About Us for just $5 a month. (no hidden fees)