On 05/09/2025 09:36 EEST Zhang Huangbin via dovecot <dovecot@dovecot.org> wrote:
On Sep 5, 2025, at 13:05, Aki Tuomi <aki.tuomi@open-xchange.com> wrote:
Running mixed system with shared folders is going to indeed be very difficult and I would strongly recommend against it. It sounds to me that you should migrate to new server with new config and just one mailbox format first.
Hi Aki,
Thanks for helping.
We migrated some accounts with large mailboxes to mdbox for better performance, hence we have mixed mailbox formats on same server.
- Would you mind sharing what the difficulties are in this case?
- Can we get it work if userdb returns required information?
- Does it mean user shared mailbox only works with maildir format mailbox?
- Does it work with Dovecot 2.3? I didn't try it before with 2.3, but since we have mixed mailbox formats in production, i tested it with 2.4 while migrating and experiencing this issue.
You can try to make it work *but* it requires that everyone has the *same* root folder for mails (mail_path). If you use something like mdbox/ and maildir/, it's not going to be possible to make it work. So use something like mail/.
Once everyone has same mail root folder, you can try to use mail_driver=auto in namespace shared. Don't use this for namespace inbox, because it will behave unexpectedly (for you) if the mailbox does not exist.
You will run into exact same issues with 2.3 and 2.4. The problem is that the shared namespace cannot know what the target user is using for mail path if you don't use the same path.
Aki