modifyFolderGrant doesn't accept name but Id

[karukera]

ZCS Open Source Edition - 6.06 - Ubuntu.

Using the cli, I was able to :

create a folder
add grants to the folder
create a mountpoint

i tried to revoke the grant by using the following command :

zmmailbox -z -m address@domain.tld mfg /Briefcase/MyFolder account grantee@domain.tld none

returns : Unable to resolve id : grantee@domain.tld

I tried using the grantee's zimbraId instead of the account and it succeed.

Is it a bug ? If so ? may I submit it to bugzilla ?