Migrate to Zimbra without risking your business using a common domain

Earlier we already talked about how you can migrate from IBM Notes / Domino to Zimbra. The variant we set out is ideal for small enterprises with a small number of employees. But what should large enterprises do with hundreds of employees, where abrupt transition to a new mail system is guaranteed to lead to a collapse and create unprecedented risks for a business? Is it possible to organize a phased transition to Zimbra in this case?



As in the case of our previous example , a phased transition will be achieved by deploying two mail systems on the same domain at once. The main difference will be that this time the Zimbra Collaboration Suite will be used as the main mail system. One of its tasks will be sending mail to the server with IBM Notes / Domino in the event that their recipients have not yet migrated to Zimbra. As a result, we need to come to such a scenario, in which a letter coming from an external network got on the Zimbra MTA, and then redirected to the email system where the addressee’s account is currently located.

So, within the framework of the existing infrastructure, we have the IBM Notes / Domino, working on the mail.company.ru domain and the Zimbra Collaboration Suite, located on the zimbra.company.ru domain. In order for Zimbra to fully perform the role of the primary server, namely to receive mail and forward it to Domino, it is necessary that accounts for all email users be created on the Zimbra server. If instead you resort to using global rules, as was the case in our previous article, then all letters that are not on the Zimbra server will be redirected to the server with Domino. This is fraught with the fact that when you receive a letter addressed to a nonexistent user, a so-called “mail loop” will arise.
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In the event that your company uses AD for account management, there should be no problem creating accounts in Zimbra. In the same case, if all the accounts are created and stored in IBM Notes / Domino, you can avoid the manual tedious manual transfer of accounts using the built-in Domino function to export the list of accounts to a .csv file. After this is done, you need to run the Bulk Provisioning Wizard , which can simultaneously create up to 500 accounts based on data from a .csv file.



After all the accounts on the server with Zimbra have been created, it is necessary for each of those who will be on the server with Domino to register the routing using a command like zmprov ma user@company.ru zimbraMailTransport smtp: mail.company.ru: 25 , where instead of user@company.ru, it is necessary to substitute the accounts “living” on the server with Domino. In principle, having a .csv file extracted from Domino with a list of accounts, you can automate this process using a script.

After this, you only need to configure your MX record so that all incoming letters are first sent to the Zimbra MTA, where they will be sorted. This completes the configuration of the shared domain for Zimbra and IBM Notes / Domino. After that, you can begin to transfer the contents of mailboxes and account data from one system to another. This is done with the help of the ZCS Migration Wizard for Lotus Domino and the instructions outlined in one of our previous articles .

Note that after completing the migration of any account from IBM Notes / Domino to Zimbra, you must disable the forced routing of letters that we set up for it earlier. This is done using the command zmprov ma user@company.ru zimbraMailTransport lmtp: zimbra.company.ru: 7025 . Thus, after all users migrate to Zimbra, the mail will no longer be redirected to the server with Domino, which means that it can be turned off and completely switched to using Zimbra.

This migration option is universal and can be used for migration from any mail system to Zimbra. It can also be used in the transition from using MS Exchange to Zimbra, if the instruction we described in the last article does not suit you for some reason.