To email a link to a Collection to a non-registered user (someone who doesn't have access to your platform), go to My Collections, select a single collection and then Click on "Share Settings". This will give you the option to email your collection to both registered and non registered users.
*Note that only resources living in folders with public sharing enabled will be sent. Folders which have public sharing enabled are displayed with a little globe icon to indicate so. If none of the resources live in folders with public sharing enabled, then no email will be sent.