In my opinion there are 3 serious newsletter plugins for WP.
And i have and used then all.
I am not consider standalones like SendFox or Sendy.

- Newsletter Plugin. Most active installs in WP. Very hard to use, not intuitive, strange workflow and bad UI/UX

- Mailster. Best Selling on Codecanyon. This is the best Newsletter Plugin for WP in my opinion. The best functionalities and you can do almost everything if you creative to go around some minor limitations.
You may need a little better than average technical knowledge to set it up the right way to do all things you need for marketing
Sometimes we get some issues/bugs that get resolved in time. But still the best in my opinion

- Mailpoet

Mailpoet might be the best choice for 80% of all people
It is simple and very, very easy to setup and use
It is so good to find a theme, plugin or software that you do some minor set up and just work without issues
And i think that has the most integrations of all: Forms, Membership, Woocommerce, etc
Advice, use Mailpoet to send Woocommerce emails so you can easly customize the design

About the "issues" with accounts being pause due to spam sending, don´t use their sending server

It is the best option for everybody

For Mailpoet, you make the deal more profitable for Mailpoet because of the non use of their servers
If Mailpoet sees it as it was profitable, might comeback or share experience with other great developers and that great developers with great software that we might already use, come to AS

It is better for YOU not use their sending servers, because you will get better delivery with companies that their main service/focus is email deliverability
Email is a serious and hard thing to deliver even for good senders
If you have some tech knowledge with Imap, SMTP and a little Javascript, instead choose companies like:

(Ordered by best delivery in my opinion with my experience)

1) Amazon AWS SES
2) Sendgrid with a private IP ( Got issues with shared IP´s being black listed )
3) Elastic Email with a private IP ( Got issues with shared IP´s being black listed )
4) Postmark (You have to be smart and good sender to use then or they will kick you out)
5) Mailgun

Some got free tiers and the best one (Amazon AWS SES) is very, very cheap

And just like David Swift from Profitable Tools says, it is better to not rely on Life Time Deals of services like email sending service, email marketing or hosting because they have high recurring costs for service that they got paid only once.

Conclusion

Buy it for a blog, a affiliate site or a small to medium online store

I got no links, just my honest opinion to help Sumolings and keep AS a good and profitable place for Great Developers, like Mailpoet.

Final words

Be smart with your sending reputation
Setup Postmaster accounts with Google and MS Outlook / Hotmail
Check the reputation of your sending IP with SenderScore
And test your emails with - mail-tester.com - the best and it it is free for 3 tests a day