Exchange 2010 Transport Rule filter test/clarification if it's works

[sukh]

1.Doing some testing and need to know if this works for others in their env.

2.Exchange 2010 SP1 (try with any RU),

3.Create a transport rule with the following conditions "from people", "sent to users that are inside or outside the organisation, or partners", "When any attachment file name matches text patterns" and specify .msg (Condition)

4.For the Action, choose " Blind carbon copy (Bcc) the message to addresses"

5.This seems to work with other file extensions but not .msg, i.e .txt, .xlsx, .doc etc...

6.If you can test this rule, would be appreciated.

[sukh]

Resolved, this is by design.