6 files declare their use of MessageNotifyException in Message Notify 8

Email.php in src/Plugin/Notifier/Email.php

EmailTest.php in tests/src/Unit/Plugin/Notifier/EmailTest.php

MessageNotifier.php in src/MessageNotifier.php

MessageNotifierBase.php in src/Plugin/Notifier/MessageNotifierBase.php

MessageNotifyTest.php in tests/src/Kernel/MessageNotifyTest.php

Sms.php in src/Plugin/Notifier/Sms.php