Migration from Cyrus

Hhuszty · Oct 19, 2020

Hi!
I just started to evaluate possible email platforms to swap out our legacy hand-wired postfix+cyrus+saslauthd+alotofotherstuff. The dockerized Mailcow seems very promising! Exactly what I’ve searching for.
The first issue is to resolve the mailbox migration from cyrus to dovecot.
My first attempt contained the following steps:

Fresh Mailcow install
Created a mailbox, then stop all Mailcow containers,
I used this tool to covert a sample mailbox on the old system with 10k+ emails: GitHub - a-schild/cyrus2dovecot: cyrus2dovecot with virtual domains and unixhierarchysep
GitHub
GitHub - a-schild/cyrus2dovecot: cyrus2dovecot with virtual domains and unixhierarchysep
cyrus2dovecot with virtual domains and unixhierarchysep - a-schild/cyrus2dovecot
Spin up a temporary container, with the mailcowdockerized_vmail-vol-1 attached
Swap the Maildir for the account with the converted stuff, fix permissions/ownerships
Delete temp container, spin up Mailcow again

Surprisingly the emails showed up right for the first attempt in the webmail.
I noticed two things: the email order is strange. The default “Order received” option gives semi-random order. “Date” option is a bit better, it gives only 15 random emails on the top, then comes the most recent emails correctly.
The other thing is that on the admin panel, the mailbox still shows 0% use.

I would have the following questions to start:

Is there a better way to migrate mailboxes from cyrus?
What metadata may be lost during such conversion?
Is there a way to re-index/recount the mailbox usage?

Thanks in advance!

jacotec · Oct 21, 2020

I’ve migrated all from IceWarp to Mailcow last weekend and I’ve used the synchronization feature of Mailcow which worked like a charm!

For this you need to have the old mailserver still up and running. Create all the mailboxed in Mailcow and set a sync job for each mailbox towards the old mailserver. Mailcow will then resync every account to the old server by default every 20 minutes.

I had all my mails and folders synced perfectly with this solution. Before the final migration I disabled port 25 to the old IceWarp (so no new emails could arrive from the outside), waited 20 minutes so all boxed had the latest sync state, and then just switched to Mailcow and enabled port 25 towards Mailcow.

I can highly recommend this feature for migrating mailboxes from any other IMAP server.

Hhuszty · Oct 21, 2020

jacotec thanks! Yeah I actually discovered the extra features of mailcow and dovecot meanwhile. Looks like this will be the way forward. It would be good to have a mass configuration for this sync, but I can do it one by one for all mailboxes as well. Thanks for the hint!