Questions about building an email list, autoresponders, etc

Hello,

I have social media accounts where I can gather a lot of emails giving my users something they want in exchange.

I need to build a website where I can collect name/email and build my list. But I also want an autoresponder that will say "Thank you for subscribing to ___ newsletter!" and also I need to add an "unsubscribe" on the bottom just in case.

Anyone here has experience doing this, what company/software do you recommend? Also, I'd like to send emails weekly to this entire list. What's the best tool to manage this?