Does the scanner send the email automatically?

No. Scanning opens a draft. The recipient must hit Send themselves. This is a deliberate safety property of the mailto: format.

What if the user has no default mail app?

Most phones handle mailto: by routing to whichever mail app the user has installed. If none is installed, the system shows a generic "No app to handle this" message. Add a mail app or pick a different QR type.

PLATE 05

SCALE 1 : 1

EDITION v0.26.10

FILE KMK·QR·05

FIGURE A · EMAIL ENCODE

Free email QR code generator

Encode a mailto: link with optional subject and body. Scanning opens a pre-filled draft in the recipient’s mail app — no need to copy your address.

Create QR code

process: client-side · zero upload
cost: free · no signup · no expiry
format: PNG · SVG · PDF
license: MIT · open source

§01

Notes on the artifact

An email QR encodes a mailto: URL — the same format you would use in an HTML link. When scanned, the phone opens the user’s default mail app with the To, Subject, and Body fields pre-filled. The user can edit before sending; nothing is sent automatically.

Subject and body are URL-encoded so spaces, ampersands, and line breaks survive the round-trip. There is no length limit imposed by the QR format itself — the practical limit is whatever the scanner’s URL parser tolerates, which is comfortably in the thousands of characters.

Use cases: a help-desk poster ("Scan to email support with the right subject line"), a print-ad reply mechanism, an event RSVP. For long-form messages, prefer encoding a URL pointing at a proper form — QR codes are not great for typing.

§02

Footnotes & queries

Does the scanner send the email automatically?: No. Scanning opens a draft. The recipient must hit Send themselves. This is a deliberate safety property of the mailto: format.
What if the user has no default mail app?: Most phones handle mailto: by routing to whichever mail app the user has installed. If none is installed, the system shows a generic "No app to handle this" message. Add a mail app or pick a different QR type.

§03

Anatomy of the code

QR ANATOMY FUNCTIONAL REGIONS DRAFTING SCHEMATIC

Every QR code is a part-functional, part-data grid. Three finder patterns at the corners let a scanner lock orientation; an alignment pattern at the bottom-right corrects perspective skew when the code is photographed at an angle. The timing patterns — alternating modules running between the finders — tell the scanner the cell pitch. Format info encodes the error-correction level and mask pattern across 15 bits arranged in an L-shape. The rest of the grid is the payload — data plus Reed–Solomon error-correction codewords. The quiet zone is mandatory whitespace; without four clear modules of margin, scanners reject the code. The detail below the main figure shows the finder pattern's 1·1·3·1·1 ring construction — proportions deliberately chosen so a scanner can recognise the pattern at any rotation, with three patterns at three corners triangulating the code's orientation.

§04