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Zimbra Migration Techniques

The Zimbra Collaboration Suite is a robust, scalable messaging server, consisting of email, shared group calendars, contact management tools and other application that are well-suited for implementation in a variety of environments, from small to very large enterprises. As examples, the H&R Block Corporation utilizes it to provide service to 100,000 end-users, and the University of Toronto uses it to service its’ tens of thousands of faculty, staff, and students (Gagné, 2007). However, in our present discussion, we are concerned with the migration of Zimbra email accounts to an Exchange Server environment.

I. Email Protocols

1.1 SMTP
To facilitate our understanding of the migration procedure, we must first perform a cursory review of the protocols that email uses. Of these, the Simple Mail Transport Protocol (SMTP) is utilized to reliably send email over its’ default TCP port 25. As it is used strictly for sending email, it typically is used in conjunction with the POP3 or IMAP protocols, which will be used to receive the email. SMTP has the ability to transport email across multiple network types such as the Internet, a LAN or WAN, as well as firewall-isolated TCP/IP Intranet, or hosts utilizing a non-TCP transport-level protocol (Klensin, 2008). For UNIX based systems, we find that sendmail will be the SMTP server of choice, whereas in the Windows environment Microsoft Exchange, which has POP3 support capabilities, would be deployed.

1.2 POP3
POP3 (Post Office Protocol 3) is a widely used protocol built in to into email products, such as Outlook Express and Internet browsers to receive email, on its’ default TCP port 110. The POP3server host will listen on Port 110, and when a client host needs to access the POP3 service, it will establish a TCP connection with the server host. When the connection is established, the POP3 server will send a greeting, and the client and POP3 server will exchange commands and responses until the connection closes or aborts (Myers & Rose, 1996). POP3 typically deletes mail on the server as soon as the user has downloaded it, though some POP3 versions allow the server to be configured to store email for a finite period.

1.3 IMAP
The Internet Message Access Protocol, Version 4rev1 (IMAP4rev1) uses TCP port 143 as its default port. As with POP3, IMAP is used to access and manipulate electronic mail messages on a server, however its’ feature-set is more robust. IMAP4rev1 will allow remote message folders to be manipulated as if they were local folders. IMAP4rev1 will also permit an offline client to resynchronize with the server (Crispin, 2003). With IMAP4rev1 the user is able to create, delete, and rename mailboxes, check for new messages, permanently removing messages, as well as store messages on the server.

1.4 PST files. Worthy of consideration when discussing migration from a Zimbra Server to an Exchange Server, are the two types of Outlook Data Files used by Outlook. These two file types are the Outlook Data File (.pst), which is delivered, to and saved on the mail server, and permit us to access our email even when you cannot connect to the mail server. The other file type is the offline Outlook Data File (.ost), which is kept on our computers.

The key distinctions between the two types are that .pst files are used for POP3, IMAP, and web-based mail accounts. When we archive or backup our Outlook folders and items on our computer, we must create and use additional .pst files. In contrast, .ost files are used when you have an Exchange account and want to work offline or work with the default Cached Exchange Mode. The .ost file may also be used with accounts set up with the Outlook Connector for Outlook.com. Finally, the .ost files are always copies of items that are saved on a mail server and do not have to be backed, as with the .pst files (“Introduction to Outlook Data Files”, 2014).

II. Zimbra Collaboration Suite
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The Zimbra Collaboration Suite (ZCS) groupware applications are available via a Web interface. Zimbra provides a client-side solution and an integrated messaging server consisting of Postfix, LDAP, Apache and other applications. These applications even may be third-party applications, such as a purchasing system (Gagné, 2007). There are a number of means to migrate from Exchange to Zimbra, and Outlook clients are fully supported, which means that all Outlook e-mail, contacts and calendar functions will work with Zimbra.

There are community supported Open Source Editions and Network Editions of Zimra. As expected, the Network Edition provides commercial support, as well as value-added features, such as clustering, advanced backup and recovery features, an attachment search function and Outlook MAPI and Apple iSync connectors.

2.1 Zimlets. Zimlets can add additional functionality to Zimbra, such as hovering over a time in an email message and having an pop-up alert you of an your appointment time. Other zimlets may launch Skype when you hover over a phone number, and one that works with an Asterisk VoIP system. There are also Yahoo! Maps zimlets, Wikipedia zimlets, Google translator zimlets, and many others.

III. Zimbra Migration Strategies

There are many instances where a Mail administrator will need to migrate users from one email server to another, as was the case with Argonne National Laboratory (ANL) that migrated their users from divisional mail servers to a central, institutional ZCS (Stacey, Trefonides, Kendall & Finley, 2009). However, it bears pointing out that by 2014 ANL had migrated their users back to Exchange servers, due to the vendor support offered by Microsoft.

3.1 Exporting Zimbra data account into CSV. As part of the migration process we will need to create users and mailboxes in Exchange. To accomplish this, we may export Zimbra data into CSV to create a list of our email users. To accomplish this, we would invoke the following commands in Zimbra:

su – zimbra

zmprov-l gaa

This will display a list of accounts, and from this, we may make a text file with the command:

su – zimbra

zmprov gaa-l> list-account.txt

However, this will only generate a list of email addresses, and not names or other fields. To export a list of Zimbra accounts to a CSV file, we would open Zimbra Admin; select Account, type the domain name that we want to export into the search box, such as contoso.com (Fahrudin, 2014). We then select the Download button on the Toolbar Zimbra Admin, and save the generated CSV file.

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