browse-url-mailto-function is a variable defined in `browse-url.el'.
Its value is

  • This variable may be risky if used as a file-local variable.

Function to display mailto: links.
This variable uses the same syntax as the
`browse-url-browser-function' variable. If the
`browse-url-mailto-function' variable is nil, that variable will
be used instead.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 24.1 of Emacs.