Last year, it was discovered that Russia had attempted to use Tumblr accounts to influence users and potentially affect the US election.

Then last week, Tumblr users who had interacted with the trolls received emails notifying them of this. The email stated that Tumblr had uncovered and terminated 84 accounts linked to the Internet Research Agency.
whoa Tumblr just a sent me a bunch of blogs I've followed at some point that they've determined were linked to Russia's Internet Research Agency https://t.co/CtZMMZuEXI