email needs no address
in your email, there is no need to attach company address or your own address, becasue it is basically a e-cover letter, however, as you will attach resume and inside which, as you know, you've got to list your address
most companies will print out emails and put them with the letter applications together and then make a short list, so it does not matter if you only send out emails as this is the faster way.
another issue is, if u are interested in two vacancies in one company, better wirte to say you are applying for one and at the same time, you can mention in your cover letter that you are open to other jobs such as blabla (the other one), so that they can judge if you are suit for both or only one etc...