I am planning to soon release an open-source research document I put together about prominent progressive voter engagement organizations such as Rock the Vote, Vote.org, League of Women Voters, Campus Vote Project, Students Learn Students Vote, etc., which are essentially harvesting emails and phone numbers for their subscription lists in the process of assisting Americans with registering to vote.
They also create an illusion that they are non-partisan. While the home pages of their websites appear non-partisan, it is clear they are set on promoting a progressive agenda when looking at the organizations they partner with and the backgrounds of their staff. Rock the Vote is obviously progressive, and is the foundation organization that has paved a path for other similar organizations to follow.
I appreciate if you can provide any information you have about third party voter engagement organizations attempting to communicate with you. There are many more than the ones I listed.