MailPoet - MailPoet is an email newsletter plugin for Wordpress.
OptinMonster - OptinMonster helps to convert abandoning website visitors into subscribers and customers.
Poptin - Create engaging and high converting website pop ups and contact forms in minutes. With Poptin, you get access to a feature-packed conversion rate optimization toolkit that converts more website visitors into email subscribers, leads, and customers.
Yournotify - Email and sms marketing platform for customer engagement
GetSiteControl - Website popup builder & email marketing suite for ecommerce
MailChimp - MailChimp is the best way to design, send, and share email newsletters.