this is due to a template error in design\standard\templates\content\tipafriendmail.tpl.
ezurl is missing there.
Something like
{concat("http://",$hostname,"/content/view/full/",$node_id)|ezurl} should work for you (if you have only one site access).
Reported as a bug here:
http://ez.no/community/bug_reports/missing_ezurl_in_template_design_standard_templates_content_tipafriendmail_tpl and fixed for 3.4.2 and 3.5.
