The events that are logged resemble the following:
Event ID: 9567
Event Type: Warning
Event Source: MSExchangeIS
Event Category: General
Event ID: 9567
Date: date
Time: time
User: N/A
Computer: ComputerName
Description: Unexpected error 0x50a occurred in "EcVirusScanOneMessage"
Event Source: MSExchangeIS
Event Category: General
Event ID: 9567
Date: date
Time: time
User: N/A
Computer: ComputerName
Description: Unexpected error 0x50a occurred in "EcVirusScanOneMessage"
Event ID: 9874
Event Type: Warning
Event Source: MSExchangeIS
Event Category: Virus Scanning
Event ID: 9874
Date: date
Time: time
User: N/A
Computer: ComputerName
Description: Unexpected error 0x80040109 occurred in "EcProcessVirusScanQueueItem" during virus scanning. Mailbox Database: /o=OrganizationName/ou=AdministrativeGroupName/cn=Configuration/cn=Servers/cn=ComputerName /cn=Microsoft Private MDB
Folder ID: 4b-1FF132F
Message ID: 4b-22192E7
Event Source: MSExchangeIS
Event Category: Virus Scanning
Event ID: 9874
Date: date
Time: time
User: N/A
Computer: ComputerName
Description: Unexpected error 0x80040109 occurred in "EcProcessVirusScanQueueItem" during virus scanning. Mailbox Database: /o=OrganizationName/ou=AdministrativeGroupName/cn=Configuration/cn=Servers/cn=ComputerName /cn=Microsoft Private MDB
Folder ID: 4b-1FF132F
Message ID: 4b-22192E7