When I studied branding and implied trademarks, the biggest point made was confusion.
If a visitor might come to your website, and mistakenly think they are @ Earn United, and Earn United has in the eyes of the law ‘branded’ the name or addy.. then you could be infringing.
For instance, if you owned a cookie shop, and I sold purses, we have the same URL (.com & .net) My customers are not likely to be easily confused, because cookies are not purses.
Thats just a basic overview though, and I’m by no means qualified to give advise.. just my understanding of the law 
~LadyH