When creating an offer, a landing page, subscription/sign up form, ask only for necessary information. People really don’t want to be bothered to fill in infinite spaces; in most cases, an email address and a name are more than enough. Ask for more info, and people won’t take time to fill it out, let alone leave their email. To successfully collect email addresses, keep it short and straightforward.
Do you have an older list that you suspect has mostly decayed? Create an engaging opt-in message and send it to your old list encouraging contacts who wish to re-opt-in -- promising to remove all contacts who don't respond. Though it might seem counterintuitive to remove folks from your email lists in order to grow them, emailing only engaged contacts could improve your deliverability and increase the odds of your email getting shared with those outside your current contacts database.
Mailjet is a tool you can use forever free for up to 6,000 emails per month! It’s an email marketing service that enables you to build, send, and monitor your email marketing campaigns at scale. With its subscription forms tool, it helps you build your audience and grow contact list with ease. The pricing for bigger lists and email marketing campaigns starts at $8.69/month.
In this context, I guess each post can’t be thought of in isolation, but in terms of a mini content ecosystem that comprises of a great blog post optimised for on-page SEO, an upgrade to that post tailored for that specific content, various on-page email conversion points including an exit pop-up or similar -and then you combine all this with your off page link building and outreach efforts. That could be over 5,000 words of content all in just that one package.