1000? That depends on any number of variables - beginning with who is on that email list? Followed by - is your product or service relevant to their needs? Is your marketing message compelling? In email broadcasting, some sectors are more receptive than others - in hosting, maybe 5-15% will actually open your email, but if you convert one or two, consider that broadcast a success.
Most of the email clients today are extremely good at blocking spam. If you think you could get a list of 1000 emails and send mails to each of them randomly I doubt any of them would convert. If they are targeted then I would say less than 5%.
Email marketing is only good if the people you are sending emails to are already your clients! For example, if you had a sign up form on your website you could get a list of targeted emails! But please don't buy a random list and expect to make money from it