GetResponse

GetResponse pairs email marketing with automation workflows, so your messages can trigger based on subscriber actions. The official WordPress plugin makes it simple to embed signup forms on any page and automatically add contacts to your lists. You can set up welcome sequences, upsells, and follow-ups without leaving your WordPress dashboard.

It works well if you're building an email list while running your WP site and want to automate follow-up campaigns. The interface is intuitive enough for beginners but powerful enough to handle complex automation as you grow.