Updating to SMG 10.5.2 Symantec Messaging Gateway (SMG) 10.5.1 was a "gated release", meaning that you would need to be on this version prior to being able to update to SMG 10.5.2. In order to install 10.5.2, you will need to either upgrade to 10.5.1 first, or use the ISO image to OS Restore a fresh image to the SMG server.
Changes to Control Center TLS Requirements SMG is additionally supported on Internet Explorer 8 / 9 browser versions on Windows Vista onward. SMG 10.5.2 requires TLS 1.2 be enabled in browsers for login and administration. Internet Explorer 11 and newer versions of Firefox and Chrome should have TLS 1.2 enabled by default. For information on how to enable TLS 1.2 for Internet Explorer 8 / 9 / 10 see here: http://www.symantec.com/docs/TECH216914
Changes to Supported Virtual Platforms VMWare ESXi 4.1 has been removed from the list of supported hypervisors for SMG 10.5.1. This is due to ESXi 4.x reaching end of support life with VMWare and its removal from general availablity. While it is expected that SMG 10.5.2 will run on VMWare ESXi 4.1 without issue, due to the vendor support status of ESXi 4.1, support for SMG 10.5.1 will partial / best effort. We recommend that customers still using the ESXi 4.x virtual platform update their virtual infrastructure at their earliest convenience to ensure full support of their SMG infrastructure.