Read the documents for your situation before you install Symantec AntiVirus on your mail server.

WARNING: If you configure Symantec AntiVirus Corporate Edition 10.x/9.x as a client on a Microsoft Exchange server or any SMTP server, be sure not to install Internet E-Mail Auto-Protect. This feature monitors the standard mail ports, and can cause performance degradation or failure if installed on mail servers.
For details, read the document for your product version:

• Installing Symantec Client Security 3.x clients or Symantec AntiVirus Corporate Edition 10.x clients without E-Mail Auto-Protect plug-ins
• Installing Symantec AntiVirus 9.0 clients without E-Mail Auto-Protect plug-ins.

Microsoft Exchange with Symantec AntiVirus Corporate Edition 10.x

• Best practices for Symantec AntiVirus 10.x Auto-Protect on a Microsoft Exchange server
• Preventing Symantec AntiVirus 10.x from scanning the Microsoft Exchange directory structure
• Symantec AntiVirus 10.1 automatically excludes Microsoft Exchange files and folders.
  For details, read About automatic exclusions of Microsoft Exchange server files and folders in Symantec AntiVirus 10.1 and Symantec Client Security 3.1.

Microsoft Exchange with Symantec Antivirus Corporate Edition 9.x

• Best practices for Symantec AntiVirus Corporate Edition 9.x Auto-Protect on a Microsoft Exchange server
• Preventing Symantec AntiVirus Corporate Edition 9.x from scanning the Microsoft Exchange directory structure

Microsoft Exchange with Symantec AntiVirus Corporate Edition 8.x

• Best practices for Symantec AntiVirus Corporate Edition 8.x Real Time Protection on a Microsoft Exchange Server
• Preventing Symantec AntiVirus Corporate Edition 8.x from scanning the Microsoft Exchange directory structure

Domino servers

• Preventing Symantec AntiVirus Corporate Edition from scanning the temporary folder for Symantec AntiVirus/Filtering 3.x for Domino or Symantec Mail Security 4.0 for Domino on a Notes Server
• Best practices for running Symantec AntiVirus Corporate Edition and Symantec AntiVirus/Filtering 3.x for Domino on the same server

SMTP gateway servers

• Preventing the scan of Symantec Mail Security 5 for SMTP product directories by Symantec AntiVirus Corporate Edition version 10.x
• Preventing Symantec AntiVirus for SMTP Gateways 3.x or Symantec Mail Security 4.0 for SMTP from being scanned by Symantec AntiVirus Corporate Edition
  If you use the Spam Quarantine feature with Symantec Mail Security 4.x for SMTP, also set the exclusions in the document Preventing Symantec AntiVirus Corporate Edition 10.x/9.x from scanning the Brightmail directory structure.

Brightmail

• Preventing Symantec AntiVirus Corporate Edition 10.x/9.x from scanning the Brightmail directory structure

If you install multiple Symantec programs that use the virus definitions on the same computer, such as Symantec AntiVirus along with a Symantec product for Microsoft Exchange or Lotus Domino, use only Symantec AntiVirus Corporate Edition to update the definitions. If you allow multiple programs to run LiveUpdate and attempt to update the definitions, the definitions may become corrupted.
For details, read Configuring LiveUpdate for multiple Symantec products installed on the same computer.