Version 7.0 system requirements.
Ensure that you meet the appropriate system requirements for the type of installation that you are performing. If you do not have Internet connection on your system, then installing Mail Security may take a long time to complete. Mail Security tries to examine the certificate revocation list (CRL) to verify the code signing certificate each time that Mail Security compiles an assembly into managed code. When Mail Security is not connected to the Internet, each CRL request may time out before the installation can continue and increases the installation time.
Mail Security supports 32-bit processors on all supported operating systems. Mail Security supports 64-bit processors on all supported operating systems except Windows XP.