Allow or Block Zip Files at Firewall

For some time we have blocked certain file types at the firewall such as script, exe and zip files. We continue to get requests to no longer block zip files. I understand that anti-virus software has gotten better at examining zip files. We currently run Barracuda spam firewalls for inbound email. With the recent escalation of malicious files in the form of zip files, what is the opinion/best practice with regard to allowing or blocking inbound zip files at the firewall?