Looking for the perfect tool for email automation as an Indie Hacker

Hello Indie Hackers!

I have several web projects underway, each with its own domain and target audience. Even though they are side-projects, each one has its own identity and they have nothing to do with each other. I find myself at a crossroads, looking for the perfect tool to help me automate email sending to my users.

My needs are: I want to be able to send an email just when a user registers on my website, send another email if the user has not entered the web for a week, or even send a discount coupon if I see that the user visits the website but does not make a purchase. I would also like to be able to assign scores to users based on their behavior and engagement with the web (what pages they visit, how often they log in, average price of their purchases, etc).

I have been investigating some tools like ActiveCampaign and Mautic. However, I am interested in hearing the experiences of other indie hackers who may have used these (or similar) tools for similar use cases.

Which email automation tool do you use and why? How has it worked for you in terms of managing multiple websites and sending automated emails based on user behavior? Would you recommend any other tool that I have not mentioned?

I appreciate in advance all your shared suggestions and experiences. Cheers!