I've got an SMTPAppender configured and I'd like to have email messages sent by that appender to have the header Auto-Submitted: auto-generated added to the messages. (This allows auto-responders, for example, to stop sending out-of-office messages to auto-generated error messages).
I don't see anything in the log4j 1.2.x API to handle this kind of thing. Is it possible to do with the existing library? If not, is it possible with a little extra hacking?
It seems as if this capability isn't available with log4j (at least the 1.x line) out of the box.
I've created a class that will do this through configuration. It can be found on GitHub here: org/apache/log4j/extras/ExtendedSMTPAppender.java