users send messages as ATT00001 with ATT00002.bin attachements with SMIME cant seem to change this

Hello,

I'm running an exchange 2013 system and we have an issue that if users sent Encrypted emails they show up on older versions of Outlook and mobile phones as ATT00001 and ATT00002.bin. It doens't matter from what client we sent it. And it is not an issue for Outlook 2013 and newer mobile phones like Vlackberry 10 or iOS8 devices, but on older devices it doesnt display correctley, and in OWA it is un readable (with S/MIME extention installed). When I look at the header it says|:

Content-Type: application/ms-tnef; name="winmail.dat"
Content-Transfer-Encoding: binary

And this is weird as I have TNEF turned off :

RunspaceId                           : 9dce606b-5c50-45bb-ab6e-a092b3a97f37
DomainName                           : *
IsInternal                           : False
TargetDeliveryDomain                 : False
ByteEncoderTypeFor7BitCharsets       : Use7Bit
CharacterSet                         : iso-8859-1
NonMimeCharacterSet                  : iso-8859-1
AllowedOOFType                       : External
AutoReplyEnabled                     : False
AutoForwardEnabled                   : False
DeliveryReportEnabled                : True
NDREnabled                           : True
MeetingForwardNotificationEnabled    : False
ContentType                          : MimeText
DisplaySenderName                    : True
PreferredInternetCodePageForShiftJis : Undefined
RequiredCharsetCoverage              :
TNEFEnabled                          : False
LineWrapSize                         : Unlimited
TrustedMailOutboundEnabled           : False
TrustedMailInboundEnabled            : False
UseSimpleDisplayName                 : False
NDRDiagnosticInfoEnabled             : True
MessageCountThreshold                : 2147483647
AdminDisplayName                     :
ExchangeVersion                      : 0.1 (8.0.535.0)
Name                                 : Default
DistinguishedName                    : CN=Default,CN=Internet Message Formats,CN=Global Settings,CN=DOMAINCOM,CN=Mi
                                       crosoft Exchange,CN=Services,CN=Configuration,DC=domain,DC=com
Identity                             : Default
Guid                                 : 64165533-258a-4c3a-b167-153b48c04eeb
ObjectCategory                       : cdomain.com/Configuration/Schema/ms-Exch-Domain-Content-Config
ObjectClass                          : {top, msExchDomainContentConfig}
WhenChanged                          : 7-5-2015 11:38:29
WhenCreated                          : 29-4-2015 15:56:38
WhenChangedUTC                       : 7-5-2015 09:38:29
WhenCreatedUTC                       : 29-4-2015 13:56:38
OrganizationId                       :
OriginatingServer                    : dc.domain.com
IsValid                              : True
ObjectState                          : Unchanged

I've tryed changing the MIME types and message encoding options but keep getting the same result,

Is there maybe some setting that overrides the exchange conversion, that I'm overlooking?