Yes and no.
No if you're e-mail the addresses bought to a third party or sending your info through a third party.
Yes if it is a opt-in e-mail list that you built yourself. That could be extremely powerful since these people opt-in because of the content you offered, or the products you sell. They are already interested on what you have to say.
No if you have already tired your recipients. Do remember that when they opt-in for the first time, they're interested on whatever you want to say. As they receive more and more e-mails from you, people will simply tend to ignore your e-mail (maybe because they don't have the time for what you offered, because they found a competitor that looked at least as interesting as your company, because life got in the middle, because they're not into whatever topic you talk about anymore, or any other thousand reasons) and send it to the bin. And, of course, even if there's no other reason... they will simply do it because the grew tired of you.
That's why knowing your customers and what they're interested and a long etc. is so important.