'all' folder msgs from last 3 weeks; of symlinks?

[Tom R]

I have many nmh folders, that get filled by procmail. I'd like to have, an 'all'
folder that is built by a shell script that could be called by cron daily. 
I'd be happy, with all msgs, say from the last 21 days. Perhaps this script
would remove bad symlinks in 'all' each time it runs.

**In this way I could use sort and 'scan' to list the nmh 'all' folder msgs 
sorted by time.**

Has someone already done this or the equivalent? Ideas/comments?

--
thanks,
Tom