The Solaris mailx(1) utility is a great command line tool for viewing mail, responding to messages, and summarizing mbox formatted mailboxes. I use the following mailx options to periodically summarize my SPAM folder, which is in mbox format:
$ mailx -H -f /export/home/matty/mail/Spam
O 1 Graham Baxter Sat Feb 26 12:50 124/4709 its your last chance!
O 2 Nina Howard Sat Feb 26 12:50 118/4390 its your last chance!
O 3 olita kane Sat Feb 26 13:00 118/5196 Generic Wlaggra
I periodically process the output of this command to see if legitimate mail was tagged as SPAM. Works well!