Is there a possibility in redmine to notificate users by email if only an issue have a text?
For example, it notificates on every event (change status, add related issues, etc..).
Can it be set to notificate only when an issue has a real text?
I don't understand your question. But if redmine is too "verbose" think of redmine silencer plugin which allows users to suppress E-Mails when editing issues.