Just received this e-mail, does not appear to be targeted. Earn 750 bonus MileagePlus miles when you sign up for MyPoints at their link and keep your membership active for 30 days.
MyPoints is a program where you get points for reading marketing e-mails, taking surveys, and they are also a shopping portal like eBates. I used to use them but haven’t for a few years as the points have gotten even more devalued to the point that I don’t bother accumulating them.
But 750 United miles is worth taking 2 minutes to sign up with a temporary anti-spam e-mail address and forgetting about it. 750 miles is 3% of a 25k roundtrip award.