There are a crazy number of different email marketing softwares out there.
So many that I felt it was worthwhile to compile them all into a publicly available post.
The Two Best Platforms for Email Marketers
ConvertKit is what I use currently to manage my 21,000+ person email list. The deliverability rates are amazing, it's simple to use and it's more than powerful enough to let you create effective tests, sequences and automations.
Active Campaign is the gold standard in 2020 for marketers who want high open rates and all the bells and whistles. It is slightly more expensive than ConvertKit but you get a much larger suite of functionality.
Every Other Email Marketing Software on the Market
These are in alphabetical order only. You will have to do your own research, but I've added links to each option for convenience.