I stumbled across a wonderful tool a few months back; unroll.me. When you link the tool to your email account it pulls an often long list of all those obscure mailing lists you had forgotten you were part of. And in 1 simple click - you can unsubscribe from them. (They ask you to share a Tweet or two in exchange). ENewsletters that you still want to receive, can be 'rolled up' into a daily or weekly curated email.