dsync_features = empty-header-workaround
imapc_host = imap.oldserver.name

imapc_user = %u

imapc_features = rfc822.size
mail_prefetch_count = 20

# tried different versions of this, where to check it?
# imapc_list_prefix = INBOX

doveadm -v -o imapc_user=old@server.name -o pop3c_user=old@server.name -o imapc_password=PASS -o pop3c_password=PASS
 -o mail_fsync=never backup -R -u new@newserver.name imapc:

dsync(new@newserver.name): Error: Can't delete mailbox INBOX: INBOX can't be deleted.
dsync(new@newserver.name): Info: Szkice: highest_modseq changed: 0 != 1
dsync(new@newserver.name): Info: Kosz: highest_modseq changed: 0 != 1
dsync(new@newserver.name): Info: INBOX: only in dest (guid=a8ca2821b25f9c587451000045e496db)
dsync(new@newserver.name): Info: Sent: uidnext changed: 7 != 1
dsync(new@newserver.name): Info: Robocze: highest_modseq changed: 0 != 1
dsync(new@newserver.name): Info: Wysłane: highest_modseq changed: 0 != 1
dsync(new@newserver.name): Error: Trying to open a non-listed mailbox with guid=a8ca2821b25f9c587451000045e496db
dsync(new@newserver.name): Error: msg iteration failed: Couldn't open mailbox a8ca2821b25f9c587451000045e496db
dsync(new@newserver.name): Error: Trying to open a non-listed mailbox with guid=a8ca2821b25f9c587451000045e496db