REST and account status

[desport]

Hello,

I need to backup accounts and restore them on another server. I try to use the REST API.
zmmmailbox -z -m user@domain getRestURL "//?fmt=tgz" > account.tgz

I would like to stop mail delivering for the user during the backup but when I change the status to maintenance (zmprov ma user@domain zimbraAccountstatus maintenance) the zmmmailbox command fails :

ERROR : service.AUTH_EXPIRED

Do you know an other way to stop mail delivering for only one user ?

Thanks.