It’s one thing to have great content on your website, or even have a fantastic newsletter, but there’s no point investing time in creating content if no one’s reading it.
One of best ways to get visitors returning to your site or reading your newsletter is with an optin form. Optin forms allows you to collect email addresses so you can alert users when you have new content or offers and get them to return to your site.
There are a bunch of different kinds of ways you can display optin forms on your site (sidebars, slide-ins, after post boxes, and squeeze pages) and you can even choose when these forms are displayed (after a specified amount of time or when they’ve scrolled to the bottom of your site).
Best WordPress Optin Plugins to Grow Your Email Subscriber List