I have a big problem with a database. I have a list of suscribers in an excel list with their names, phone and other info. I need to import that suscribers to my drupal website and use them for send them massive emails. How to do that? which newsletter module is better for use with my usecase?
Try the feeds module, or migrate for importing the data. Whatever module you end up understanding best for newsletters, is what I recommend.
Your question leaves out various details: show email templates be editable by site moderators or users, opt-in or opt-out features for the newsletters. Are newsletters recurring, or sent on-demand ... etc.
I recommend looking at the various newsletter modules, Rules based modules and scheduler modules to see what fits your needs.
I find leveraging an existing solution, like mailchimp and other email services typically well worth the cost (personally).
As example I wrote custom code that looks at emails in an imported DB table and uses a server-side cron task to run a Drush command to send emails with my own custom business logic (recurring scheduled emails, if tasks are completed they no longer receive emails)... my solution is not for everyone.