All Messaging Gateway (SMG) version 10.6 releases reached end of support life (EOSL) in December 2019.
All SMG version 10.7 releases have a projected End of Service date of December 5, 2027.
SMG 10.6 was released at the end of November 2015 and exceeded its four year support lifespan in December of 2019.
Please see the Product Lifeycle tab of the Messaging Gateway product support page for definitive end of service (EoS) dates for the SMG product.