Every year, we get an e-mailed invitation from my husband's cousin for her 4th of July barbecue. This "e-vite" typically states that the hosts will provide basic items like hot dogs and chips, then goes on to state that guests should bring their own beverages (any kind, not just booze) and also says something to the effect of "if you wish to join us for dinner, you should bring......" filled in with either "a dish for everyone to share" or sometimes a specific item. Last year, the e-vite actually stated that they were going to have the party, but due to economic hard times, our guests need to bring......then went on to list everything, down to chairs/forks/napkins, etc.
My question is two parts: One, is it rude to even use e-mail for the invitation in the first place, and two, is it rude that they would invite you to a party and then basically tell you that if you want something then you need to bring it with you?
I'm confused because it is a barbecue, so technically an informal party, but she doesn't specify "potluck" so much as just tells the guests that they need to bring something.