What happens when a phone scans an email code
The code holds a mailto: link, the standard way to describe a new email. It looks like mailto:[email protected]?subject=Question%20about%20my%20order. A phone that scans it offers to open its mail app with a new message already addressed, with the subject and text in place.
Which app opens is the one the phone uses for mailto: links: Mail on an iPhone and often Gmail on an Android phone, and you can change it in the phone's settings. A phone with no mail app or account set up may do nothing, and people who only use email in a web browser may see nothing happen. If your audience is mixed, print the address in words next to the code.
The message is only a draft. The person can edit it and has to press send, so a code cannot send email on its own.
Pre-filled fields that save work
A subject and a message turn a blank email into one you can act on. A few ways to use them:
- Feedback or support: a subject such as
Feedback from table 12tells you where it came from before you open it. - RSVPs and sign-ups: a message such as
I will come to the open day. Names:saves the sender thinking what to write. - Quotes and enquiries: add a line asking for the details you always need, such as size, date and place.
Do not try to put a long form in the message. Every extra sentence makes the code denser. If you need more than a few lines of structured answers, a form on a web page is a better fit, and you can link to it with a link QR code.
Cc, Bcc and who can read the addresses
Cc and Bcc work as they do in a normal email: the person's mail app puts the addresses in those fields when the message opens. But the code itself stores every address as readable text. A Bcc is therefore not hidden from anyone who scans or photographs the code. Use Bcc only for an address you do not mind being seen.
The same goes for the main address. Anyone can read it from the code, just as they can from an address printed on a poster, so use a role address such as hello@ or support@ rather than a private one.
Line breaks, accents and the size of the code
Line breaks in the message are kept. Line breaks in the subject are turned into spaces, because a subject is one line.
The subject and message are written into the link in a safe form. A space becomes three characters (%20), a letter such as é becomes six, and an emoji becomes twelve. That is why a short message in plain English makes a much smaller code than the same message with accents or emoji.
As a guide at medium error correction, an address alone is 25 by 25 squares, an address with a subject and one short sentence is about 45 by 45, and an address with a subject and a short paragraph is 61 by 61. Some phones and mail apps also limit how long a link they accept, so keep the message to a few lines.
For colours, error correction and print size, see the QR code generator page.