The heart of Zimbra is mailboxd, a big Java application. Zimbra ships with Java, and Java Garbage Collection (“GC”) settings tuned with defaults that are suboptimal for Zimbra mailbox servers supporting demanding environments: large mailboxes (up to 200GB per user), users who regularly send and receive large attachments (up to …
Optimizing Zimbra on Amazon Web Services – Applicable to Ubuntu Server 20/22 and Rocky Linux 8/9 Overview We have been deploying Zimbra on Amazon Web Services (“AWS”) for a number of years. At the Americas Zimbra Partners’ Conference a few years ago, we were asked to present on “AWS Best …
Sharing in Zimbra is an incredibly useful collaboration feature. We have customers with more than 40K shared email folders; users report sharing enhances productivity and streamlines workflow processes. Broken shares can cause performance issues, slow web client loading and sometimes even prevent a user with broken shares from logging in …
Deploying autodiscover records in public DNS simplifies adding a Zimbra account to any device. This blog post will show you how. Introduction Yes, we like the Zimbra web client very much (and are even starting to like the Modern UI too — though that’s another blog post…). But, sometimes you …
Many customers, regulated or not, use Zimbra to ensure privacy and control data sovereignty. Unfortunately, using Microsoft’s “New” Outlook creates de facto privacy breach and data sovereignty violations when connected to any non-Microsoft email services. To get straight to the point, we strongly recommend that users concerned about privacy and …
This blog post covers Zimbra 10.1 Licensing Server (“LDS”) best practices from the more than 20 Zimbra 10.1 installations/upgrades completed to date, combined with some technical deep-dive sessions and 1:1 conversations with senior engineers at the June 2025 Zimbra Global Partners Summit (where we won — for the second year …
In April 2025 I opened a Support Case with Zimbra, which resulted in Zimbra issuing ZBUG-4827: Contact Ranking fetch causing slowness. This is an AutoComplete (Contacts Ranking Database) bug. This blog post will help you identify if your Zimbra system is subject to this bug, and your options for addressing …
At some point, you will suffer a Zimbra account breach and an email flood. This blog post will describe how to handle this situation. Do I Have A Zimbra Account Breach? Once a Zimbra account breach happens, if you are monitoring your mail queues, you will see the Deferred queue …
While Fail2Ban’s automation works great, we find that reviewing the “Recipient address rejected” section of Zimbra’s Daily Mail Report yields evidence of potential Advanced Persistent Threats as well as probes from senders whom you’d like to block. Manually grepping through /var/log/zimbra.log* on the logger host to find the sender’s IP …
Enhancing Email Deliverability for B2B senders’ outbound transactional and marketing emails was a core track at last week’s InboxExpo. This post covers several key takeaways to help you improve your B2B email deliverability. In case you missed it, to further reduce spam and domain spoofing specifically, Google and Yahoo (affectionately …
