TIL: mailto Header Fields
Last updated: Wed Feb 05 2025
I recently added a “reply by email” button at the bottom of each of my posts. You might see it at the bottom of this very post! It’s pretty simple — although it’s styled as a button, it’s actually an <a> tag with an href set to mailto:[email protected], so clicking it pops open your email client.
Although I haven’t received a response (yet), it would be nice if the email subject was autofilled to the actual post that’s being responded to. It turns out that’s trivially easy with mailto: links!
You can add header, subject, cc, bcc, and even body as query parameters, which are then autofilled in the email client. So now the button at the bottom links to mailto:[email protected]?subject=${encodeURIComponent("Reply to " + title)}, which URL-encodes the title of the post. Neat!