Build a mailto: link
A mailto link with a Japanese subject typed straight into the address fails in a confusing way: it works on your computer and arrives empty on someone else’s. Converting the text correctly is routine work, so let the tool do it.
- Runs entirely in your browser
- Works offline
- No upload
- No sign-up
- No watermark
Loading the tool…
How it works
- Fill in the address and any of the other fields.
- Copy the link address (href), or the ready-made HTML link.
- Test it with the “Open it” link — it opens your own mail program with everything filled in.
Why nothing is uploaded
Every operation on this page is done by code running inside your browser tab, using the same engine that renders web pages. The file is read from disk into your tab’s memory, transformed there, and written back out as a download. It is never sent anywhere — not to us, not to a third party.
Verify it yourself
- Open your browser’s developer tools (F12) and select the Network tab.
- Load your file and run the tool.
- The only requests you will see fetch the tool’s own code — and, for a few heavy tools, their open-source engine from a public CDN — plus one small page-view ping to loreatec.jp (page address and title, nothing more). None of them carry your file.
Frequently asked questions
Why does my hand-written mailto link lose the subject?
Because spaces, & signs and Japanese characters that are not converted (percent-encoded) cut the link short or break it. Everything after the first plain space can be lost, and Japanese text that is not converted is read differently by every mail program. The rule is simple: every value after the ? must be percent-encoded in UTF-8, and line breaks must be %0D%0A.
Does bcc work?
Not reliably. Several mail programs, including some versions of Outlook, silently drop bcc from a mailto link. It is generated here because it is part of the standard, but never build anything that depends on it — and certainly not privacy.
Is there a length limit?
Not in the standard, but in practice long links get cut short by some mail programs and some webmail services, and Windows has had its own limits on the length of a link passed to a program. Keep the body short; if you need a long template, put it on the page and let people copy it.
Should I put my address in a mailto link at all?
It is the most usable option for the visitor and the most harvestable for a spammer. If the address is one you can retire, publish it. If not, obfuscate it or use a contact form — there is an obfuscator on this site that explains how much each method buys you.