setup a meeting with them. See what they offer and try to get some info about their vision and strategy. If the deal is to weak then turn it into a "nice to meet you let's chat about our progress in the future". If it's a good deal then you'll be in a better place to answer your own question.

Just an email with "are you for sale" means nothing. You shouldn't even read it unless you're willing to hear about a potential offer.