Hello list, currently I'm migrating our old mailserver to a new mail architecture that is based on a master-master dovecot setup (two machines). The replication actually works but I'm also syncing our mails from the current mailserver via imapc on a regular schedule. For some reason I've in most (but not all) imapc-synced mailboxes duplicated emails that I also can't deduplicate with doveadm. I've also set up test-mailboxes that I don't sync with imapc and in those I don't have any duplicated mails. My command to sync the mails from the old host to the master-master system looks as follows: doveadm -o imapc_user=$i*dovemig -o imapc_password=<password> -o imapc_host=<oldhost> -o imapc_features="rfc822.size fetch-headers" -o mail_prefetch_count=20 -v -D sync -R -u$EMAIL imapc: &> $LOGS/$i.log So, is this actually the wrong approach to sync mails from the old host to the new one or is it just not recommended to sync them over-and-over again in such a setup via imapc or is it better to sync them only once? Any hint/pointing me to the right solution is greatly appreciated. Michael