The Browse-URL package allows you to easily follow URLs from within
Emacs. Most URLs are followed by invoking a web browser;
‘mailto:’ URLs are followed by invoking the compose-mail
Emacs command to send mail to the specified address (see Sending Mail).
The command M-x browse-url prompts for a URL, and follows it.
If point is located near a plausible URL, that URL is offered as the
default. The Browse-URL package also provides other commands which
you might like to bind to keys, such as browse-url-at-point and
browse-url-at-mouse.
You can customize Browse-URL's behavior via various options in the
browse-url Customize group. In particular, the option
browse-url-mailto-function lets you define how to follow
‘mailto:’ URLs, while browse-url-browser-function lets you
define how to follow other types of URLs. For more information, view
the package commentary by typing C-h P browse-url <RET>.