Growing your email list is so incredibly important. This cannot be overstated. You should be collecting emails from Day 1. This is an amazing way to get people to your site, share your messaging, and also SELL. I've tried MailChimp and MailerLite, and didn't realize what I was missing out on until these tools.
ConvertKit
BEGINNER - DISCOVERY PHASE
ConvertKit has a free version that has amazing features.
Drip
INTERMEDIATE - GROWTH & EXPANSION PHASE
Drip is my email provider because I can split the account for my four blogs easily.