Im going to do it with:
/usr/bin/curl -s -k -u admin

assword https://zimbraserver:7071/home/${ACCOUNT}@yourdomain.de/?fmt=tgz | /bin/zcat | /bin/gzip -9 --rsyncable > ${TEMPDIR}/${ACCOUNT}/${ACCOUNT}.tgz
(cd ${TEMPDIR} && /usr/bin/rdiff-backup ${ACCOUNT} ${BACKUPDIR}/${ACCOUNT} )