To resolve the issue, configure the MSA Real-Time Scan:

1. Open the Registry Editor (regedit.exe).
    

   Always back up the whole registry before making any modifications. Incorrect changes to the registry can cause serious system problems.
   ​
2. Go to HKLM\Software\TrendMicro\ScanMail for Exchange\CurrentVersion.
3. Update the ABBypassAgingMail registry key to skip attachment blocking for email messages received before <x> days.

   Name: ABBypassAgingMail
   Type: REG_DWORD
   Value: 0-Disable, In days

   If the default setting is Disable, specify the period to skip older messages in days.

   Example: Set the value to "30" to skip attachment blocking of an email message that arrived before 30 days.

    

   This registry key only affects real-time/on-access scan.
4. Update the CFBypassAgingMail registry key to skip content filtering for email messages received before <x> days.

   Name: CFBypassAgingMail
   Type: REG_DWORD
   Value: 0-Disable, In days

   If the default setting is Disable, specify the period to skip older messages in days.

   Example: Set the value to "30" to skip content filtering of an email message that arrived before 30 days.

    

   This registry key only affects real-time/on-access scan.
5. Restart the TrendMicro Messaging Security Agent Service.