We're pleased to announce that Zimbra Collaboration Suite 4.5.7 has been released.

This release includes 219 bug fixes and enhancements. You can view the full list here: Zimbra Product Portal
We strongly encourage all users to upgrade their existing installation to 4.5.7.

The most notable feature(s) are lots of stability enhancements for Tomcat and LDAP.

Network Edition users can download the latest version here:
http://www.zimbra.com/products/downloads.html

Open Source Edition users can download the latest version here:
SourceForge.net: Files