Exchange 2010 - ActiveSync - Block Attachment Iphone

I administrator an Exchange Server 2010 envoriment. I need to block attachment on devices using activesync. Is working fine on Android devices for example, but not working on Iphone devices. On all Iphone devices, users can download email attachments.

Some informations:

[PS] C:\>Get-ActiveSyncMailboxPolicy
AllowNonProvisionableDevices             : True
AttachmentsEnabled                       : False
IsDefaultPolicy                          : True
Name                                     : Default
ExchangeVersion                          : 0.1 (8.0.535.0)
IsValid                                  : True

[PS] C:\>Get-ActiveSyncDeviceStatistics
DeviceType                    : iPhone
DeviceID                      : ApplDV6JT189DTD1
DeviceUserAgent               : iOS/6.1 (10B142) dataaccessd/1.0
Status                        : DeviceOk
DevicePolicyApplied           : Default
DeviceActiveSyncVersion       : 14.0