Well, zmmailbox will only show a single mailbox at a time. So a simple for loop (or some other more efficient way) over the zmprov -l gaa output could work for you. I don't know how many accounts you have on your servers so this may (or may not) take a while to complete.
Now, I don't have much experience (or knowledge) in shell scripting, so don't bite my head off when I ask "can you do the math to turn bytes into MB in the one line?". |