Troubleshooting Course Content Rough Drafts-Zimbra Architecture Component Overview

Zimbra Architecture / Component Overview

Architecture Overview

The Zimbra Collaboration architecture is built with well-known open source technologies and standards based protocols. The architecture consists of client interfaces and server components that can be ran in a single node configuration or deployed across multiple servers for high availability and increased scalability.


Zimbra architecture includes open-source integrations using industry standard protocols. The third-party software listed below is bundled with Zimbra software and installed as part of the installation process.

  • OpenLDAP software, an open source implementation of the Lightweight Directory Access Protocol (LDAP) that stores Zimbra system configuration, the Zimbra Global Address List, and provides user authentication. Zimbra can also work with GAL and authentication services provided by external LDAP directories such as Active Directory
  • Postfix, an open source mail transfer agent (MTA) that routes mail messages to the appropriate Zimbra server
  • Jetty, the web application server that Zimbra software runs in.
  • MariaDB database software
  • Lucene, an open source full-featured text and search engine
  • Autonomy, Inc., a third-party source that converts certain attachment file types to HTML
  • Anti-virus and anti-spam open source components including:
    • ClamAV, an anti-virus scanner that protects against malicious files
    • SpamAssassin, a mail filter that attempts to identify spam
    • Amavisd-new interfaces between the MTA and one or more content checkers
  • James/Sieve filtering, used to create filters for email
  • LibreOffice for high-fidelity document preview

Zimbra Ldap - OpenLdap

  • What is OpenLdap

OpenLDAP Software is an open source implementation of the Lightweight Directory Access Protocol/OpenLDAP is a free, open source implementation of the Lightweight Directory Access Protocol (LDAP) developed by the OpenLDAP Project.

  • What is it used for

LDAP is a protocol for accessing a directory. A directory contains objects; generally those related to users, groups, computers, printers and so on; company structure information/LDAP gives you query methods to add, update and remove objects within a directory

  • How does Zimbra use OpenLdap

  • The importance if OpenLdap

Zimbra MTA - Postfix

  • What is a MTA

A Message Transfer Agent or Mail Transfer Agent or Mail Relay is software that transfers electronic mail messages from one computer to another using a client–server architecture. An MTA implements both the client (sending) and server (receiving) portions of the Simple Mail Transfer Protocol (SMTP ) port 25.

  • What does it do

A Mail Transfer Agent receives mail from either another MTA or from a MUA. The transmission details are specified by the Simple Mail Transfer Protocol (SMTP). When a recipient mailbox of a message is not hosted locally, the message is relayed, that is, forwarded to another MTA.

  • How does Zimbra use a MTA/Postfix specifically

Zimbra uses postfix for its Mail Transfer Agent. Postfix is a free and open-source mail transfer agent (MTA). Postfix is secure and easy to configure and maintain.

Zimbra Reverse-Proxy - NGINX

  • What is a Reverse-Proxy

a reverse proxy is a type of proxy server that retrieves resources on behalf of a client from one or more servers. These resources are then returned to the client as though they originated from the proxy server itself.

  • What is Nginx and why we use Nginx

Nginx (pronounced engine-x) is a free, open-source, high-performance HTTP server and reverse proxy, as well as an IMAP/POP3 proxy server.

  • How does Zimbra utilize Nginx for large scale environments
  • The importance if Nginx

Zimbra Mailbox Server - "Mailboxd"

  • What is a Mailbox Server

The Zimbra mailbox server is a dedicated server that manages all the mailbox content, including messages, contacts, calendar, and attachments. The Zimbra mailbox server has dedicated volumes for backup and log files. Each Zimbra mailbox server can see only its own storage volumes. Zimbra mailbox servers cannot see, read, or write to another server.

  • What is it
  • How does Zimbra use the Mailbox Server

DataStore IndexStore MessageStore

  • The importance of the Mailbox Server

Zimbra AntiSpam/Antivirus - Amavisd - SpamAssassin - ClavAV

  • What is AmavisD, SpamAssassin, ClamAV

amavisd-new is a high-performance interface between mailer (MTA) and content checkers: virus scanners, and/or SpamAssassin. SpamAssassin is used for e-mail spam filtering based on content-matching rules. SpamAssassin uses a variety of spam-detection techniques, that includes DNS-based and fuzzy-checksum-based spam detection, Bayesian filtering, external programs, blacklists and online databases. ClamAV is an open source anti-virus engine used in a variety of situations including email scanning, web scanning, and end point security. It provides a number of utilities including a flexible and scalable multi-threaded daemon, a command line scanner and an advanced tool for automatic database updates.

  • What do they do
  • AmavisD - amavisd-new is a high-performance interface between mailer (MTA) and content checkers: virus scanners, and/or SpamAssassin. (
  • How does Zimbra use Amavis, SA, ClamAV
  • The importance and the requirement

Zimbra Client architecture

  • Web Clients
  • Zimbra offers a standard HTML, advanced Javascript, a mobile client, or touch client that users can log into to use Zimbra. The web clients include mail, calendar, address book, and task functionality. Users can select the client to use when they log in.
  • Advanced Web Client includes Ajax capability and offers a full set of web collaboration features. This web client works best with newer browsers and fast Internet connections.
  • Standard Web Client is a good option when Internet connections are slow or users prefer HTML-based messaging for navigating within their mailbox.
  • Mobile Client (Native Mail Client) is used to configure and sync the Zimbra mailbox server with the native mail client on a mobile device.
  • Touch Client (Mobile Web App) provides an experience for touch-capable mobile devices. Its features are a subset of the features found in the Zimbra Web Client, including Mail, Contacts and Calendar.
  • Mobile HTML Client provides mobile access to Zimbra when using the Standard Web Client version.

When users sign in, they view the advanced Zimbra Web Client, unless they use the menu on the login screen to change to the standard version. If ZWC detects the screen resolution to be 800 x 600, users are automatically redirected to the standard Zimbra Web Client. Users can still choose the advanced *ZWC but see a warning message suggesting the use of the standard ZWC for better screen view. When connecting to Zimbra using a mobile web browser, Zimbra automatically detects and defaults to the Touch Client. To use the Mobile Client, you must configure your mobile device to sync with the Zimbra server.

  • Web Services and Desktop Clients
  • In addition to using a web browser or mobile device to connect to Zimbra Collaboration, connection is available using a web service, such as Exchange Web Services (EWS), or a desktop client such as Zimbra Connector to Microsoft Outlook, which uses MAPI. The following are supported:Exchange Web Services (EWS) provides client access to enable Zimbra Collaboration to communicate with the Exchange Server when using Microsoft Outlook on a Mac device. To enable EWS client access, see the Class of Service section. EWS is a separately licensed add-on feature.Messaging Application Programming Interface (MAPI) synchronizes to Microsoft Outlook 2013/2010/2007/2003 with full delegate, offline access and support for S/MIME. Use the Zimbra Connector to Outlook to connect to Zimbra Collaboration when using Microsoft Outlook on a Windows device. To enable MAPI (Microsoft Outlook) Connector, see the Class of Service section.Support for all POP3, IMAP4, Calendaring Extensions to Web Distributed Authoring and Versioning (CalDAV), and vCard Extensions to Web Distributed Authoring and Versioning (CardDAV) clients.

  Offline ModeZimbra Offline Mode allows access to data without network connectivity when using the Zimbra Web Client (ZWC). For example, if there is no server connectivity or server connectivity is lost, ZWC automatically transitions to “offline mode”. When server connectivity is restored, ZWC automatically reverts to “online mode”. The offline mode uses HTML5, which uses a caching capability that can be considered a super set of the normal browser caching. To enable offline mode support, see the Class of Service section.

Quiz Questions

  • What is Postfix?
  • How does Zimbra use Postfix
  • How does the client communicate with the Proxy?
  • How does the client communicate with the Mailbox Server?
  • What is AmavisD?
  • How does Zimbra utilize AmavisD as a AntiSpam/AntiVirus?

Verified Against: Zimbra Collaboration Suite 8.6 Date Created: 01/22/2015
Article ID: Date Modified: 2015-03-01

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