I'm just getting going with JBoss and Log4j.
How about having each JBoss instance generate its own string identifier. Then when you use Log4J to log the event that generates the email, include the string identifier in the log message.
From the looks of the appender setup, it doesn't seem like it's possible to customize the text for the email subject on each logging action.
Incidentally, can you elaborate on your setting for the email appender. I can't get it going on a Windows XP machine. Specifically, what value for the SMTPHost are you using? Is this the IP address of your POP3 provider?
Also does the BufferSize value mean the queue? I assume a value of 1 means send out the email immediately, 5 would mean wait for 5 messages before sending. Right?
<param name="SMTPHost" value="localhost"/>
<param name="BufferSize" value="10"/>