rsync: Unknown --usermap name on receiver for AD user

I'm trying to move files to a new fileserver which is a samba4 domain member using rsync -a. Unfortunately the uid and gid are not mapped correctly. The files on the target get the uid from the source. So I tried to force the correct mapping by using --usermap=3000019:'DOMAIN\myuser' but then I get

Unknown --usermap name on receiver: DOMAIN\myuser

uid and gid mapping is working as expected:

getent passwd 'DOMAIN\myuser'
DOMAIN\myuser:*:10001105:10000514:My User:/share/homes/DOMAIN/myuser:/bin/false

or

id 'DOMAIN\myuser
uid=10001105(DOMAIN\myuser) gid=10000514(DOMAIN\domain users)

Does anyone know how to handle domain users with rsync correctly?