I found what I think is a better way of releasing quarantined emails (at least until bug 47625 is fixed), using zmlmtpinject.
/opt/zimbra/bin/zmlmtpinject -s <envelope_sender> /opt/zimbra/data/amavisd/quarantine/virus-whatever -r <recipient>
Note that <recipient> can be a list.
Full documentation on zmlmtpinject is here:
how can I use zmlmtpinject? - Zimbra :: Forums
Shouldn't be too hard to script a solution that just takes the filename and then parses it for the envelope sender and recipient list. (Or envelope sender can just default to postmaster@<your_domain>.)