We have a user that has a mac. He wants to be able to edit distribution groups in exchange. I have logged into OWA as him and gone to options, more options, then selected "manage my organization". From there, selected distribution groups, then membership, however the "+ADD" and the "-REMOVE" fields are missing. Other options are greyed out. See screenshot.
In exchange, he is the "managed by" for the distribution groups in question. I am able to do this when logged in as the administrator, so believe this to be a permission setting.
By the way, this is Exchange 2010.