I would suggest to edit ebuild >=mail-filter/qmail-scanner-2.05 if its compiled with clamav on the system to use --qs-user=clamav which is not actually happening. In this manner you do not need to configure clamav, freshclam and clamd to run as qscand and have all files owned by qscan user but you can run clamd and qmail-scanner naturally. This is much more better if you use clamd to scan via modules for another software. Reproducible: Always
clamav already works with qmail-scanner, reading files via group permission