How do you send emails to various recipients? What services do you use for that?
There are many good services like Mailtrap, Sendgrid, Mailgun
Besides third-party services you can use this options:A built-in PHP mail() function;PHPMailer;Symfony Mailer;All info about them you'll find in Mailtrap article. It is useful guide with info about the basic PHP email sending principles, syntax, and parameters and the main ways of sending emails with PHP.