You install and configure Microsoft Forefront Protection 2010 for Exchange Server (FPE), Microsoft Forefront Security for Exchange Server (FSE), Microsoft Forefront Security for SharePoint (FSSP), Microsoft Antigen 9.0 or Sybari Antigen 8.0. After you do this, users in your organization receive e-mail messages stating that an attached file has been removed because of its "Large Uncompressed Size characteristics."

This issue occurs if the following conditions are true:

• The Delete Corrupted Compressed Files check box is selected in the General Options work panel in Antigen, FSE, or FSSP. In FPE, the Delete Corrupted Compressed Files option is selected in Policy Management, under Global Settings, in Advanced Options.
  
  To view this setting, follow these steps.
  
  For Antigen, FSE, or FSSP
  1. Start the Antigen Administrator program.
  2. In Shuttle Navigator, click General Options.
  3. In the General Options work panel, notice that the Delete Corrupted Compressed Files check box appears under Scanning.
  For FPE
  1. In the FPE Administrator Console, click Policy Management, and then click Advanced Options under Global Settings.
  2. In the Global Settings - Advanced Options pane, notice the Delete corrupted compressed files option under Deletion Criteria. This option is enabled by default.
  
  
  
• The affected user received an e-mail message that has the following characteristics:
  • The e-mail message contains an attachment.
  • The attachment is in a compressed format. For example, the attachment is compressed in a .zip archive.
  • The uncompressed size of the message attachment exceeds the value that Antigen is configured to allow for in compressed message attachments. By default, this value is 100 megabytes (MB).

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

If you are severely affected by this issue, you can modify the uncompressed file size for compressed message attachments that are allowed by FSE, FSSP, FPE, or Antigen. This size is controlled by the "MaxUnCompressedFileSize" registry entry in FSE, in FSSP, and in Antigen and by the “Maximum uncompressed file size (megabytes)” Advanced Options setting in FPE.

The registry entry for FSE and for FSSP is found at the following locations: The registry entry for Antigen is found at the following location: To modify this setting in FSE, FSSP, or Antigen, follow these steps:

1. Click Start, click Run, type regedit, and then click OK.
2. Locate the appropriate registry subkey, depending on whether you have FSE, FSSP, or Antigen installed.
3. In the right pane, right-click MaxUnCompressedFileSize, and then click Modify.
4. In the Edit DWORD Value dialog box, click Decimal. Then, type the number that corresponds to the number of bytes to which you want to restrict the uncompressed file size of message attachments. By default, this value is set to 100000000. This corresponds to 100 MB.
   
   For example, to restrict the uncompressed size of message attachments to less than 200 MB, type 200000000 in the Value data box. To restrict the uncompressed size of message attachments to less than 53 MB, type 53000000 in the Value data box.
   
   Note In this registry entry, do not calculate the total number of MB by using a base value of 1024.
5. Click OK, and then exit Registry Editor.
6. In FSE or FSSP, stop and then restart the FSCController service. To do this, follow these steps:
   1. Click Start, click Run, type services.msc, and then click OK.
   2. In the Services Microsoft Management Console (MMC) snap-in, right-click the FSCController service, and then click Stop.
   3. After the FSCController server stops successfully, right-click the FSCController service, and then click Start.
7. In Antigen, stop and then restart the AntigenService service. To do this, follow these steps:
   1. Click Start, click Run, type services.msc, and then click OK.
   2. In the Services Microsoft Management Console (MMC) snap-in, right-click AntigenService, and then click Stop.
   3. After the AntigenService service stops successfully, right-click AntigenService, and then click Start.
   Note We recommend that you use the Stop command and the Start command instead of the Restart command to restart the AntigenService service.

To modify this setting in FPE, follow these steps:

1. In the FPE Administrator Console, click Policy Management, and then click Advanced Options under Global Settings.
2. In the Global Settings - Advanced Options pane, change the value for the Maximum compressed file size: (megabytes)under the Threshold Levels section.
3. Click Save.