as I’m working at the moment over a dsync solution for my mailserver reading a lot of documentation - that’s what I’ve found:
dsync is running at a per user base so you will see in the tachtler-script something like:
if [ ! -n "$FILE_USERLIST" ]; then
log "Check if the variable FILE_USERLIST is set ................[ NO ]"
log "Mailboxes to backup will be determined by doveadm user \"*\"."
for users in `doveadm user "*"`; do
You can also find a warning concerning shared and public folder in the dovecot-wiki https://wiki.dovecot.org/Replication :
WARNING : Shared folder replication doesn’t work correctly right now – mainly it can generate a lot of duplicate emails. This is because there’s currently a per-user lock that prevents multiple dsyncs from working simultaneously on the same user. But with shared folders multiple users can be syncing the same folder. So this would need additional locks (e.g. shared folders would likely need to lock the owner user, and public folders would likely need a per-folder lock or a maybe a global public folder lock). Fixing this is currently low priority for Dovecot developers.
doveadm sync also knows the option
-m for a mailbox-sync. The script then would have to be extended to also backup this mailbox.
It isn’t a solution yet, but perhaps the reason why the script won’t backup this mailbox.