SMTP has no authentication, authorization, or encryption built in. GSM and the verizon standard do. SMTP abuse is entirely down to you being able to fire and

SMTP has no authentication, authorization, or encryption built in. GSM and the verizon standard do. SMTP abuse is entirely down to you being able to fire and forget a message without any sort of acceptance criteria for downstream systems. Anyone abusing the mobile network runs the risk of their provider pulling the plug and disabling their access.