Centralize all mail servers into one


I have 4 servers, 2 of them running mails for their assigned domains; another has a production online store running, as well as the store’s staging environment. The fourth server has been recently migrated from centOS / Cpanel to Ubuntu / Virtualmin.

The fourth server is practically idle, as it has shallow usage (of course, it’s not a very powerful server, only 1 GB ram and 40 GB HD).

I think it might be wise to concentrate all the emails of all the domains into that server so that I can have just one single administration point for postfix rules and management instead of replicating settings between two different servers.

I have 11 different domains.

The mail usage is low.

I’d like to ask if anyone could suggest the best course of action to achieve this centralization effort?

I want this change to be as seamless as possible for my users.

Thanks for the time to read this.

Operating system: UBUNTU
OS version: 20.04

The same thing was discussed about one week ago.


If you move mail away from a server, its efficiency to serve web pages will increase significantly. I would recommend this for all who run multiple Virtualmin servers.

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I appreciate your comments.

Do you have any suggestions as to how could I do this in a seamless way? I’d rather not interrupt my domain’s day to day operation.


If you want to move mail to another server, provision the new server serve as your mail server for the domain, setup all user mailboxes, then update the MX record for that domain pointing it to the new server.

*** Depending on how you setup email client configurations, you may or may not need to adjust settings in the email client to reflect the new server. ***

Once you’ve confirmed DNS propagation has completed, you can safely “rsync” the mailbox data from “old” to “new” server. This is how we move stuff around for large scale servers with enormous mailboxes and heavy traffic without disrupting email delivery. There are ofcourse other techniques both simple and more complex which can accomplish this task.

Feel free to reach out to me if you find this task daunting and want an expert to assist in the process.

Best Regards,
Peter Knowles | TPN Solutions

Thank you so much for your reply and your offer.

I wonder: If I use Virtualmin’s function “Transfer Virtual Server”, then implement a two-way rsync between mailboxes, and finally do the DNS change, keeping both mail services running until the final DNS propagation… wouldn’t that be as transparent as possible for the users?

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