What I am interested in is finding out whether or not the actual blockchain.com has been in touch with you regarding your domain? It's so similar that it's difficult to avoid confusion, especially when the link to whatever page you refer people to is long and people only read the part that says
https://blockchain.com.
From a trademark perspective, Blockchain.com can't do anything.
They did file a lawsuit against Blockchain.io, but that was based on supposed infringement of their
logo. Apparently, they have no legal basis to go after anyone for use of the word "blockchain" because it's a generic term not protected under trademark law:
Their use of the word blockchain isnt really protected under U.S. Trademark law
Perhaps because they couldnt get protection for the word, they filed a design mark blockchain in all capital letters with a picture next to it. And even though they dont have trademark protection for the word, it appears that they are in effect by this lawsuit trying to use their design mark to prevent blockchain.io from using the word blockchain.
-Stephen Palley, an attorney with corporate law firm Anderson Kill P.C.