Just got one this morning. It had me pretty shook until I noticed a couple warning signs - poor capitalization, no evidence or indication of the copyrighted photos in the email body, the fact the notice was sent through a website form and seemingly not submitted to Squarespace's copyright email, and identical wording to other scams cited. I also noticed that they used the name of a person who has a photography business, but the email address doesn't match the one listed on their business page.
If Squarespace received a legitimate notice of infringement, it would contact the individual itself or flag the claimed media until action was taken, wouldn't it?
Stay safe out there!
