Reporting application Errors by Email

Good article about log4j and reporting critical events
Reporting Application Errors by Email by Sean C. Sullivan --
Even if your application logs an error to a local file, the developer doesn't know there's a problem until a user notices it and sends the log file back.
It can be more useful for apps to email their own error messages back. And as Sean C. Sullivan explains, it's not hard to do with either log4j or java.util.logging.