How to add a QR code to an email signature

Should it be there at all?

Quick honesty check first: the recipient is already on a device where links are clickable: a QR code in an email mostly serves the printed email, the projected email, or the phone-scans-desktop-screen handoff. The cases where it earns its pixels (and the ones where it does not) are covered on the email signatures surface page. If you are here, you have a case; on to the how.

1. Choose the payload

• vCard: recipient scans, your contact card opens ready to save. The strongest signature use, since it does something a link does not do well.
• URL: booking page, portfolio, LinkedIn. Keep it short; signature codes are small, and longer payloads mean denser codes.

2. Use a hosted image URL, not an attachment

Signature editors accept images two ways, and the difference matters:

• Hosted URL (right): the signature references an image by URL. The keyless API link is itself a stable hosted image: paste it wherever the editor asks for an image address:

https://useqr.app/api/v1/qr?data=https://example.com/book&size=240

• Embedded/attached image (avoid): some editors inline the file, which triggers attachment icons on every mail you send and gets stripped by some corporate gateways.

In Gmail: Settings → See all settings → Signature → insert image → Web Address (URL). In Outlook and Apple Mail: paste or drag the image into the signature editor. These embed it; acceptable, just test a sent mail. Company-wide rollouts through signature-management tools take the URL form natively.

3. Size: small, but not too small

Signature codes render around 100–120 px, which is roughly 2.5–3 cm on a typical display, comfortably scannable by a phone pointed at the screen, and printable at just about the 2 cm floor if the email is printed at 100%. Below ~80 px rendered, dense vCards start failing, trim the vCard to name, one number, one email, one URL rather than shrinking further.

4. The dark-mode trap

The single biggest signature-specific failure: dark-mode email clients transform images. Outlook's dark mode inverts light images, turning your code into a light-on-dark inversion that scanners reject, and other clients dim them. Defences:

• Use a code with a solid white background (never a transparent one, which inherits the dark client background directly).
• Send test mail to accounts in Outlook dark mode, Gmail dark mode and Apple Mail dark mode before rolling anything out to a team. The general logic is the same as QR codes on dark-mode websites.

5. Test the round trip

Send yourself the email, then: scan the code off the received message on another phone, check it in dark mode, forward it once (forwarding sometimes recompresses), and print it. Paste the image URL into the validator to confirm the payload is exactly right: a signature ships thousands of times, so a typo ships thousands of times too.

Gotchas

• Remote-image blocking: Outlook and some corporate setups hide remote images until the reader clicks "download pictures": one more reason the code should supplement, not replace, the plain-text details in your signature.
• Reply chains shrink and sometimes strip signatures; expect the code to be scanned from first-contact emails, not thread number nine.
• Keep alt text ("Scan to save my contact details") so blocked-image and screen-reader cases still convey what the block is: see alt text guidance.

Generate the signature code: a vCard code for contact saving, or a URL code for bookings.

FAQ

How do I put a QR code in my Gmail signature?

Settings → See all settings → Signature, insert image, choose Web Address (URL), and paste a hosted QR image URL such as a UseQR API link. Size it around 100–120 px.

What should an email signature QR code link to?

A vCard is the strongest choice, scanning saves your contact details straight to the phone. Otherwise a short booking or portfolio URL. Avoid anything with a long tracking-parameter tail.

Why does my signature QR code fail in dark mode?

Some clients, notably Outlook, invert or dim images in dark mode, producing a light-on-dark code most scanners reject. Use a solid white background and test in dark-mode clients before rollout.

Is a QR code in an email signature even useful?

Only for print, projection and cross-device moments, recipients on the same device can just click a link. It earns its place when you want screen-to-phone handoff, such as saving a contact.