Issues with syncing of shared mailboxes

Hello,
I have a two users, that have a personal mailbox and a shared mailbox.
They have access  to the same shared mailbox.

Today they notified me, that a mail send to the shared mailbox exists 
for the one user but not the other.
The user also notified me, that some mails are not being delivered.

I haven't found anything in my log files and the postmaster has also no 
delivery failures.
I relay my mails through another server I don't have access to though.

My /etc/aliases only consists of `postmaster: root`. The relay owners 
said that I should change postfix' main.cf to `double_bounce_sender = 
postmaster` a while ago. I am also not sure if I am not getting any 
delivery failure notifications since then, since I don't have a 
`postmaster` account, but I thought this is not needed since I have the 
above line in `/etc/aliases`.

I also tried forcing a resync of their shared and non-shared inboxes 
with: `doveadm force-resync -u [email protected] INBOX` as well as 
`doveadm force-resync -u [email protected] Shared` (as well as with 
`Shared\*` - I don't know if that makes a difference tbh).

Here is the output of `dovecot -n`: 
https://bin.disroot.org/?4eac9ea90a72ff08#A2dim9VGqHAjjKcggF4ScFWpbGytePZjtKee8V5E8XUL

I am kind of lost where to start from here, because any other person I 
asked told me their mail worked fine ^^.

I would highly appreciate some guidance :)

Thank you.
Best,
Lucienne
_______________________________________________
dovecot mailing list -- [email protected]
To unsubscribe send an email to [email protected]