scan.YYYYMMDD (to try to regain space taken by extra date info) was
ill-conceived. It's not that tough to get past 999 messages, though I imagine
it's rather rare to exceed 9999. Changed these to 4. I had already removed the
"replied / encrypted" column in YYYYMMDD, but this time I removed it on MMDDYY
as well (I've never seen it used...).