What the code contains
A mailto: URI with URL-encoded subject and body. Scanning opens the default mail app on phones and the default handler on desktop — usually Outlook, Apple Mail or Gmail.
Keep the body short
mailto payloads grow quickly because spaces and punctuation are percent-encoded (a space becomes %20, three characters). A 60-character subject plus 200-character body can push the QR past a comfortable density. If you need a long message, encode a short landing-page URL instead.
Good uses
- Conference badges with a 'email me' action
- Product packaging for warranty registration
- Print ads where typing an address is a barrier
- Internal signage for IT or facilities requests
Desktop behaviour
On desktop browsers, mailto may open a webmail compose window or prompt for an app. Test on the platforms your audience uses — behaviour varies by OS and default-handler settings.
Frequently Asked Questions
Does it send the email?
No — it opens a compose window; the user reviews and sends.
Why is my subject garbled?
Some mail clients mis-handle percent-encoded UTF-8 in mailto. Stick to plain ASCII in the subject.
Can I use multiple recipients?
Technically yes with commas, but it is a poor experience; link to a form instead.
Privacy & Your Data
CSSmith runs entirely in your browser. Whatever you type, paste or upload is processed on your own device and never sent to a server — there is no backend to store it.