Custom Variable

Say i have an email form on Lighthouse and Lighthouse , how would i go about tracking emails sent for different pages?

Create a goal for each URL, then manually call piwikTracker.trackGoal( X )
with X being the goal ID, on each page, after an email was submitted.

see: http://piwik.org/docs/javascript-tracking/#toc-manually-trigger-a-conversion-for-a-goal