Win Rar Attachment blocked with errors

Hello Experts,

I have Exchange 2010 with SP3 Roll Update 3 with Forefront installed on it.

I have a user who was trying to send an email with attachment in 5 MB size and it is win rar compressed file.

but the internal and external users are receiving as text

This is the error

FILE QUARANTINED

The original contents of this file have been replaced with
this message because of its characteristics.
File name: 'winmail.dat->File.part3.rar'
Malware name: 'CorruptedCompressedFile'

Please can someone help to resolve this.

Thanking in advance.