Setup dovecot sync along the lines of (https://wiki2.dovecot.org/Replication). I am doing one way replication.
The initial full replication happened without issue, but now I'm seeing these errors on the slave server:
doveadm: Warning: /data/mail/foo/bar/Maildir/dovecot-uidlist: Duplicate file entry at line 26397: 1562173159.M215923P17350.mxp,S=2290,W=2339 (uid 143128 -> 143142)
Warning: Failed to do incremental sync for mailbox Sent Messages, retry with a full sync (Modseq 1766 no longer in transaction log (highest=17617, last_common_uid=17559, nextuid=17560))
Warning: Failed to do incremental sync for mailbox INBOX, retry with a full sync (Modseq 2540 no longer in transaction log (highest=13870, last_common_uid=19912, nextuid=19913))
I guess dovecot automatically tries a full replication because eventually the messages get pushed and "sync failed" status changes from 'y' to '-'