Social Bookmarking is a fancy name for Social Share for the stream items. It is a process of tagging website page with social network so that you can easily visit it the future. This feature allows you to integrate and display social share buttons on your site.
This options are located at EasySocial > Settings > General > Social Bookmarking as shown in the following screenshot.
Apart from bookmarking with social network, you can also sent it to any email recipient. You may specify the Limit Number Of Emails Every Hour for this feature.