02 Migrate from remote courier (on LAN) to dovecot localhost

tovis@tst10:~$ sudo doveadm -D -o imapc_user=tovis -o pop3c_user=tovis -o imapc_password=<password> -o pop3c_password=<password> backup -R -u tovis imapc:
Debug: Loading modules from directory: /usr/lib/dovecot/modules/doveadm
Debug: Skipping module doveadm_acl_plugin, because dlopen() failed: /usr/lib/dovecot/modules/doveadm/lib10_doveadm_acl_plugin.so: undefined symbol: acl_user_module (this is usually intentional, so just ignore this message)
Debug: Skipping module doveadm_expire_plugin, because dlopen() failed: /usr/lib/dovecot/modules/doveadm/lib10_doveadm_expire_plugin.so: undefined symbol: expire_set_deinit (this is usually intentional, so just ignore this message)
Debug: Skipping module doveadm_quota_plugin, because dlopen() failed: /usr/lib/dovecot/modules/doveadm/lib10_doveadm_quota_plugin.so: undefined symbol: quota_user_module (this is usually intentional, so just ignore this message)
Debug: Skipping module doveadm_fts_lucene_plugin, because dlopen() failed: /usr/lib/dovecot/modules/doveadm/lib20_doveadm_fts_lucene_plugin.so: undefined symbol: lucene_index_iter_deinit (this is usually intentional, so just ignore this message)
Debug: Skipping module doveadm_fts_plugin, because dlopen() failed: /usr/lib/dovecot/modules/doveadm/lib20_doveadm_fts_plugin.so: undefined symbol: fts_user_get_language_list (this is usually intentional, so just ignore this message)
Debug: Skipping module doveadm_mail_crypt_plugin, because dlopen() failed: /usr/lib/dovecot/modules/doveadm/libdoveadm_mail_crypt_plugin.so: undefined symbol: mail_crypt_box_get_pvt_digests (this is usually intentional, so just ignore this message)
doveadm(tovis)<1049><>: Debug: auth USER input: tovis system_groups_user=tovis uid=1000 gid=1000 home=/home/tovis
doveadm(tovis): Debug: Effective uid=1000, gid=1000, home=/home/tovis
doveadm(tovis): Debug: Namespace inbox: type=private, prefix=, sep=, inbox=yes, hidden=no, list=yes, subscriptions=yes location=Maildir:~/Maildir
doveadm(tovis): Debug: maildir++: root=/home/tovis/Maildir, index=, indexpvt=, control=, inbox=/home/tovis/Maildir, alt=
doveadm(tovis): Debug: brain M: Namespace  has location Maildir:~/Maildir
doveadm(tovis): Debug: Namespace : Using permissions from /home/tovis/Maildir: mode=0700 gid=default
dsync(tovis): Debug: Effective uid=1000, gid=1000, home=/home/tovis
dsync(tovis): Debug: Namespace inbox: type=private, prefix=, sep=, inbox=yes, hidden=no, list=yes, subscriptions=yes location=imapc:
dsync(tovis): Error: Failed to initialize user: Namespace '': Mailbox list driver imapc: missing imapc_host