Email marketing: Opt in or Opt out

[ShopkeeperVicki]

I am bumping up against a limit with Mailchimp, so before I start paying more for my newsletter distribution, I am wondering about "scrubbing" the list.

I have pretty good stats: on average 35% open/10% clickthrough

So, here's what I would like input on:
1. Leave well enough alone
2. Ask subscribers to opt in again with an email/landing page campaign
3. Email subscribers telling them that they can opt out with the unsubscribe link at the bottom of the email, or do nothing and continue to receive the newsletter.

What say you, Shopifiers?