Being able to send reliable newsletters from your site is a complex issue to deal with. There are a number of plugins out there for sending out email newsletters from your site.
One of the best options for being able to send email newsletters is the AcyMailing plugin.
The AcyMailing plugin adds a clean UI into wp-admin after the plugins have been installed and activated.
Also, remember to import any existing users you have as well as create your lists. The users would be imported into your site and then set to a specific list. You can also manually add users as well on your site in AcyMailing.
You can set which subscription options you want in AcyMailing for how subscription on the site for WordPress, specific plugins like WooCommerce will have opted into specific newsletters.
AcyMailing has a very complete set of help articles that will ask any questions you might have about setup, creating a list, importing users, or creating and sending campaigns.
You can track how campaigns are being sent in the queue listings in the AcyMailing menu.
AcyMailing does have options for how user’s data is collected it is GDPR compliant.
The AcyMailing plugin uses a number of custom database tables to store data in.
The AcyMailing plugin offers a whole number of features and is a solid plugin option for sending out email newsletters.