Due to the :after rule in print.css all emails are printed as "caption [link]". If there was no extra caption given by the author in xhtml.php name (caption) is set to address (link). This results in "link [link]" on your print-out! The same happens for external links.
I suggest the following to fix this for emails:
Give links which have a caption an extra CSS class which is later used in print.css to attach the link in the printout.
See attached patch.