request: qmail-qfilter to use mkdtemp()

Hi!

I'm almost ready to ship a refactored SMTP AUTH implementation for 
qmail: https://schmonz.com/qmail/acceptutils

One of my goals with it is to apply user-specific filters to submitted 
messages. For example, if the user has pymsgauth configured, 
"qmail-qfilter-pymsgauth" tags submitted messages.

This works beautifully -- iff I chmod qmail-qfilter's TMPDIR wide open, 
which is obviously terrible.

Until now, qmail-qfilter has reasonably expected to always run as the 
same user (typically qmaild). My SMTP AUTH implementation breaks this 
expectation because it runs ofmipd/qmail-smtpd as the authenticated user 
(just like qmail-popup and qmail-pop3d).

My request: Bruce, would you be willing to release an updated 
qmail-qfilter that makes (and cleans up) a temporary subdirectory at 
runtime?

Thanks,

- Amitai