Is there any way to block an IP address on login failure rather than doing an account lockout? We have had to deal with a number of dictionary attacks on other systems, and the volume of attempts at times acts as a DOS with all the checks the server has to do.

I have used denyhosts with very good effect to prevent this problem with ssh:

DenyHosts

I am hoping to find a similar solution for Zimbra where a certain number of failures will put the failing ip address in /etc/hosts.deny for a period of time.