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Zimbra Selective Postfix Rate Limiting To Improve Email Deliverability

In this post, we’ll show you how doing selective Postfix rate limiting will improve your Zimbra system’s email deliverability. Various trade press accounts have reported that COVID resulted in email volumes essentially doubling.  For large email providers, especially the free email providers like Gmail, Yahoo and Outlook.com, they have had …

How To Defend Zimbra Against Distributed Brute Force Login Attacks

Increasingly we are seeing distributed brute force login attacks on our Zimbra hosting environment, as well as on our on-premises customers’ Zimbra systems. These login attempts typically come from 10 to 20 or so different IP addresses from around the globe, and are infrequent enough that Zimbra’s Denial of Service …

Architectural Design Reference for Large Zimbra Deployments in Amazon Web Services

This post documents a high-level architectural design reference for hosting large Zimbra deployments in Amazon Web Services cost-effectively, with a high degree of security, performance, redundancy and resiliency — and with very short RPO (Recovery Point Objective) and RTO (Recovery Time Objectives) targets. For single-server installations, you can still use …

Zimbra Patching – Recommended Best Practices 2019

During yesterday’s Zeta Alliance call, Zimbra Patching, recent Zimbra exploits and their mitigation were a featured topic of discussion.  The Zimbra forums have some very active discussions about mitigating currently compromised systems, so I thought it would be timely to summarize the current status of the current compromise, Zimbra’s reactions …

Java Improvements Make Upgrading Zimbra Attractive

Zimbra 8.8.12 quietly replaced Java 8 with Java 11, and combined with a change in Java Garbage Collectors, we are seeing significant mailbox server performance improvements just from doing an upgrade to 8.8.12. Key Takeaway If your mailbox servers are swapping but you believe you should already have sufficient RAM; …