Does it send the email automatically?

No, and it could not. Scanning opens a draft in the person's mail app with the fields filled in. They still have to press send, which is the behaviour you want.

Can I put line breaks in the message?

Yes. They are encoded and most mail apps keep them. A few older Android clients flatten a draft to one line, so do not rely on formatting.

Why does the encoded value look full of percent signs?

Spaces and punctuation have to be percent encoded in a mailto link. The mail app decodes them back, so the person sees normal text.

Email QR Code Generator

Scanning opens a draft, already addressed.

Send to

Subject

Message

Download as

pngsvg

Scanning opens a draft, already addressed.

How to use it

Enter the address. This is where the email will be sent. It is the only field that has to be filled in.
Add a subject and message. Both are optional. Anything you type here appears as a draft the person can edit before sending.
Download it. PNG for screens, SVG for print. The exact mailto value is shown underneath so you can check it.

When you would use this

An email QR code is a mailto link stored as a pattern of squares. Scanning it opens a new message with the address filled in, and optionally a subject and body as well, which saves someone copying an address off a poster and mistyping it. It is useful on parcels for returns, on equipment for support requests, and on signage where a prefilled subject line tells you which sign the person scanned. Nothing is sent automatically: the draft opens and the person presses send themselves. Keep the message short, because every character makes the pattern denser and a long body produces a code that needs printing large to stay readable.

Questions

Does it send the email automatically?: No, and it could not. Scanning opens a draft in the person's mail app with the fields filled in. They still have to press send, which is the behaviour you want.
Can I put line breaks in the message?: Yes. They are encoded and most mail apps keep them. A few older Android clients flatten a draft to one line, so do not rely on formatting.
Why does the encoded value look full of percent signs?: Spaces and punctuation have to be percent encoded in a mailto link. The mail app decodes them back, so the person sees normal text.