I found this under Tips and Tricks. If you want you could add HP-UX.

Regards Lars My alert emails come without a subject Hobbit by default uses the system mail command to send out messages. Solaris mail-command does not understand the "-s SUBJECT" syntax that Hobbit uses. So you get mails with no subject. The solution is to change the MAIL setting in etc/hobbitserver.cfg to use the mailx command instead. Hobbit needs to be restarted after this change./p>

I'm not young enough to know everything. -Oscar Wilde