Implementing Global Signatures for Outgoing Emails via GMS/ActiveSync

The entire premise of this email is that there is no solution to add a graphic signature/logo to GMS/ActiveSync (mobile) emails. If this is possible please let me know how. 

OK. from my observations, mobile users utilizing ActiveSync seem unable to include signature images or a logo in their outgoing emails when using an android or iphone. Is this accurate?

I'm aware that I can attach a signature through the web client and desktop client, but i cannot find a wat to do this on mobile.

Is there a way for GW to identify if an outgoing email originates from GMS and automatically append a unique global signature?