After doing more research into what my options are, I decided to instead use markdown and gimli to create a pdf which I could then attach to the resulting email.
I also added an "Email body: " prompt so that the user could incorporate a message instead of just the pdf attachment. Nevertheless, I am open to any more suggestions (possibly instead of having the code attached as a pdf, include it in the body of the email?
-> actually was able to use html to do this, but without syntax highlighting [for those who are interested, I used google-code-prettify: http://code.google.com/p/google-code-prettify/ ]).
(defun email_mark (addr subj body)
(interactive "sEnter email address: \nsEnter email subject: \nsEnter email body: ")
(let* ((default-directory "/files/")
(fname-no-ext (substring fname 0 -3))
(pdf-file (concat fname-no-ext ".pdf"))
(snip (buffer-substring (region-beginning) (region-end)))
(lang (if (equal "emacs-lisp" (substring (format "%s" major-mode) 0 -5)) "lisp")))
(write-region (format "```%s\n%s\n```" lang snip) (region-end) fname)
(shell-command (format "gimli -f %s -outputdir %s" (concat default-directory fname) default-directory))
(shell-command (format "echo '%s' | mutt -s '%s' -a '%s' -- '%s'" body subj (concat default-directory pdf-file) addr))))
(global-set-key "\C-x\m" 'email_mark)