Recommended newfs settings for 600GB mail (maildir) store?

[Chris St Denis]

I recently created a new mail server with a 600GB raid5 partition to 
store maildirs. When I created it, I used a newfs -i 4096 but when I had 
recent hardware problems the background FSCK took a very long time, and 
I'm concerned that the -i 4096 may have made that a lot worse.

So I ask. What newfs settings do you recommend for a 600GB partition 
dedicated to maildirs?