Description
My team and I are running E2E tests with Cypress and we are checking if an email has been sent (intercepted and saved on the filesystem) by checking the filesystem.

It works fine with SwiftMailer (Spool Using a File), but we have planned to migrate to the Mailer component and we don't see anything similar in the documentation.

Example

Add support for file protocol, the next part is the directory where emails will be stored:

# config/packages/test/mailer.yaml
framework:
    mailer:
        dsn: 'file://%kernel.cache_dir/emails'

What do you think?
Thanks!