Symfony Mailer VS event-dispatcher

But if you don't mind using composer, the symfony/mailer library is really easy to use and reduces headaches when it comes to sending e-mail. Can be used easily outside of symfony too and I use it for scripts like your own regularly.

Most hosting providers also provide SMTP that you can use, if you have one. Or, there are plenty of online services with a free tier that you can use. Stuff like Sendgrid, Mailchimp, Postmark and SparkPost just to name a few (those services usually provide a SDK to integrate, or can be used with something like symfony-mailer).

That is utterly simple, and can be readily converted for usage with cURL through PHP without loading any external libraries. No symfony/mailer. No PHPMailer/PHPMailer. Nothing.

Symfony Mailer - A powerful library for creating and sending emails.

It is relying on symfony/mailer to send emails and is recommended as replacement for now deprecated SwiftMailer.

While composer does have this limitation in that packages are published by making new tags within the repo, frameworks like symfony and cakephp have workarounds where they have one monorepo where all packages are worked on, and then automation to push changes to read only repos of each component. So there's https://github.com/symfony/symfony pushing to https://github.com/symfony/event-dispatcher which gets published to packagist.