Eu gosto de quase tudo que tem a ver com CK. É fácil, é simples, não tem um monte de coisas que você não precisa e ainda assim é robusto e muito fácil de usar.

They are easy to use, have great customer service

Convert kit makes it easy to set up newsletters, email autoresponders (visually) and the A/B testing is so easy to understand to someone who has a huge phobia of tech (like me.) When I was too lazy to set up a website, Convertkit was a lifesaver because they allow you to create landing pages and I was able to start collecting emails before I ever laid a finger on my website. I tried two other email systems before convertkit and the deliverability is waaaaay better. My email open rate went up but my emails didn't change. It's one of the reasons I am definitely sticking with convertkit. Last, the support with convertkit is amazing!!! They are fast and super polite. There are very few companies whose support I am impressed with but they are definitely one of them. I had a billing error happen around June and they fixed it in less than 30 minutes.