Markup: "mailto" links, possibly with optional Subject, not rendering correctly

[kenlunde]

In Source Han Sans and other projects in our organization, the use of _mailto_ is not working, perhaps when an optional Subject is specified.

The following is specified: [Dr. Ken Lunde](mailto:[email protected]?subject=[GitHub] Source Han Sans)

This is expected to be rendered as only _Dr. Ken Lunde_, but when clicked, will initiate an email in the default email client with "[GitHub] Source Han Sans" specified as the default Subject.

Instead, I see the literal markdown, per the screenshot below:

This happens regardless of the Browser: Chrome, Firefox, and Safari running on macOS Version 10.12.3.

[shawnajean]

Hey there! 👋 This actually has to do with URL requirements per the CommonMark spec. CommonMark does not allow for spaces in URLs, so you need to encode those as %20 in order for this to be a valid URL:

[Dr. Ken Lunde](mailto:[email protected]?subject=[GitHub]%20Source%20Han%20Sans)

Dr. Ken Lunde

You can review CommonMark's definition of a URL (link destination) here:

https://github.github.com/gfm/#link-destination

[kenlunde]

Thank you!

[AlexdeBorba]

Thank you for posting this.

I was here battling to figure out how to add support e-mail to the README.md

[emersonpessoa01]

Thank you!! because of your explanation. Helped me make this link:

general code:
<a href="mailto:[email protected]?"><img src="https://img.shields.io/badge/gmail-%23DD0031.svg?&style=for-the-badge&logo=gmail&logoColor=white"/></a>