On Jul 12, 2020, at 4:17 PM, Kishore Potnuru <kishore.reachme@gmail.com> wrote:

Hi All,

I need to migrate the complete data & setup/environment from an old dovecot environment to a new dovecot environment.

I did a similar move recently—I don’t have a step-by-step guide but it was pretty straightforward. My recommendation is to get the mail copied before working on the HA/Resilience part of the migration.

In the new environment, I have 2 servers. I have got 2 of the above servers with above configuration and need to create HA/Resilience. I know there is advanced versions in Redhat and Dovecot. As per my organisation's existing support/policy, that is what maximum supported RHEL and official version of dovecot as per RHEL 7.7.

Now my questions are:

1. I will stop the dovecot/postfix services on the server in old environment. Is it possible to move/copy the complete configuration along with data (directories/sub-directories/users/groups/existing email in new or cur folders/complete email domains along with complete structure) to the other 2 servers in new env? Could you please suggest me the commands or steps follow that?

The steps I followed:

1. Configure postfix and dovecot on the new server using the old configuration as a GUIDE. Make sure you know why you need a setting before blindly copying it over.

   — I wanted to reuse the old hostnames on the new servers so I named the new machine newXXXX (where XXXX is the original host name). You may not want to do that — I also took this as an opportunity to cleanup some configuration pain points (e.g. I moved the blacklist from inside my amavisd.conf file to an external file)

2. Setup DNS A (and CNAME if necessary) records with the new machines.

3. Test the new configuration to make sure it receives mail correctly and IMAP (and POP3) clients work correctly. Test the new servers with mail server testing services (particularly making sure you are not an open relay). Test that outgoing mail works correctly (recommend using a mail server testing service and not regular email services).

4. Make sure you test again.

5. If you have this already configured, setup replication on the old and new dovecot servers.

6. Use doveadm backup to move existing mail from the old server to the new server.

7. Do that again

8. Change your DKIM record to relaxed

9. At a time of the day when your users are typically idle, shutdown postfix.

10. Update DNS records (e.g. add new server to MX, take off old server from MX, update A, CNAME, reverse records if you are reusing the hostname). Don’t forget to update SPF and DKIM records.

11. Wait for the changes to propagate (could be an hour).

12. Use doveadm backup to move mail from old server to new server (very few if any messages will be transferred)

13. Test incoming messages (you could be getting new mail already)

14. Test outgoing messages

15. Test again

16. If possible, use doveadm backup to replicate mail from the new server to the old server (or setup automatic replication)

17. When you feel comfortable (at least a week) decommission the old email server.

18. Make sure you have been backing up and that they work (replication to separate dovecot instance can be part of backup solution).

19. Implement HA and Resiliency

20. Change your DKIM record to something stricter than relaxed

2. Now, With the above 2 servers, I would like to create the HA/Resilience. I know there is a Replication options which are there. Could you please provide me the steps/video, how it needs to be done?

The dovecot documentation is pretty straightforward. I recommend that you do it over TCPS. I created a CA and made client certificates signed by that CA. That way only my certificates worked.

I have got the systems and I need to move/copy the environment to a new environment and create the HA/Resilience. I am not sure, how to proceed and what needs to be done clearly? I am stuck here.

Hope that helps

Please help me in this step by step procedure.

Thanks, Kishore Potnuru