mailto is a hypertext transfer protocol and its address uses URI scheme. Therefore, its format is the same as the URL of HTTP, such as mark@example.com?subject=xxx&body=xxx.
<a href="mailto:ismk@protonmail.ch?subject=Title&body=Hi,Markbuild%0D%0A%0D%0A{content}%0D%0A%0D%0AThank you">Test</a>
encodeURI('\r\n') // Output '%0D%0A' is the escape sequence for a line break.URI
