Problem/Motivation
Even if I do my utmost to configure the modules I'm met with this disappointing text when testing:
Drupal\Component\Plugin\Exception\PluginNotFoundException: The "phpmailer_smtp" plugin does not exist. Valid plugin IDs for Drupal\mailsystem\MailsystemManager are: simple_mail, webform_php_mail, php_mail, test_mail_collector in Drupal\Core\Plugin\DefaultPluginManager->doGetDefinition() (line 53 of core/lib/Drupal/Component/Plugin/Discovery/DiscoveryTrait.php).
Drupal\Core\Plugin\DefaultPluginManager->getDefinition() (Line: 16)
Drupal\Core\Plugin\Factory\ContainerFactory->createInstance() (Line: 83)
Drupal\Component\Plugin\PluginManagerBase->createInstance() (Line: 378)
Drupal\phpmailer_smtp\Form\SettingsForm->sendTestEmail() (Line: 355)
Drupal\phpmailer_smtp\Form\SettingsForm->submitForm()
Steps to reproduce
Drupal 9.3.7
PHPMailer SMTP 2.0.3
Mailsystem 4.3.0
PHPMailer 6.6.0
Configure PHPMailer SMTP at /admin/config/system/phpmailer-smtp
Configure Mailsystem at /admin/config/system/mailsystem
Test configuration at /admin/config/system/phpmailer-smtp
Boom! You get the above error.
Trouble is: at the Mailsystem config page I can only choose these senders
simple_mail, webform_php_mail, php_mail, test_mail_collector.
There's simply no phpmailer_smtp to choose.
Proposed resolution
Saving the config at /admin/config/system/phpmailer-smtp should result in phpmailer_smtp being available as an option at /admin/config/system/mailsystem