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.

1. Start Internet Explorer.
2. On the Tools menu, click Internet Options.
3. Click the Advanced tab, and then locate the Security section.
4. Uncheck Check for publisher’s certificate revocation and then click OK.
5. After the installation is complete, check Check for publisher’s certificate revocation.
   Note: The Check for publisher's certificate revocation option is set on a per-account basis.

• Windows Server 2008 with SP2 (64-bit) Standard or Enterprise Edition
• Windows Server 2008 R2 (64-bit) Standard or Enterprise Edition

• Windows Server 2008 R2 with SP1 (64-bit) Standard or Enterprise Edition
• Windows Server 2012

• Windows Server 2008 with SP1or later (64-bit) Standard or EnterpriseEdition
• Windows Server 2003 with SP2 (64-bit) Standard or Enterprise Edition
• Windows Server 2003 R2 (64-bit) Standard or Enterprise Edition

• x64 architecture-based processor that supports Intel Extended Memory 64 Technology (Intel EM64T)
• x64 architecture-based computer with AMD 64-bit processor that supports AMD64 platform
• Exchange Server MAPI client and Collaboration Data Objects 1.2.: Requirement for mailbox role of Exchange Server 2007 only
• 1 GB of memory for Mail Security in addition to other system and software requirements.
• Approximately 4GB or more of memory is required.
• 1 GB disk space is required for Mail Security. This space does not include disk space required for items such as quarantined messages and attachments, reports, and log data.
• .NET Framework version 3.5
• MDAC 2.8 or higher
• DirectX 9 or higher
• Microsoft Internet Information Services (IIS) Manager
• Microsoft .NET Framework 3.5 and Microsoft Windows Powershell 2.0: Requirement for Exchange Server 2010 only 

• Windows Server 2003
• Windows Server 2003 R2
• Windows XP
• Windows Vista
• Windows Server 2008
• Windows Server 2008 R2
• Windows 7

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.

• Memory: 1 GB
• Available disk space:1 GB
• .NET Framework Version 2.0
  Ensure that .NET Framework is installed before you install Mail Security.
• Information Services (IIS) Version 6 or later
  You only need IIS if you install Mail Security Console on a 64-bit operating system.