Forefront deletes multi part compressed file

I have Microsoft Forefront Security for Exchange installed on the Exchange servers. One of the clients was trying to send an email with a multipart compressed file in the attachments
and he got this error:

FILE QUARANTINED

The original contents of this file have been replaced with
this message because of its characteristics.
File name: ‘winmail.dat->FileName.part1.rar’
Virus name: ‘CorruptedCompressedFile’

This happens because Forefront deletes multipart compressed files because Forefront treats them as a corrupted files.

To get this issue solved do the following:
In Forefront Server Security Administrator, under Settings, click General Options.
Under Scanning, click to clear the check box beside "Delete Corrupted Compressed File".