Incoming Arabic, Greek emails are read as Garbage

[MPFL]

I have a 3rd party application that I use to read emails.

All incoming emails that contains Arabic, Greek, or even French letters (é) are being read as garbage.

In my software there is an option to check "Encode using 8 Bit" and that's it.
but it didn't solve the problem.

I have done some research and read that Even if an application encodes with 8 Bit but Windows encodes with 16 bit and that might be the problem.

I am using a Windows XP Service Pack 2.
Have installed Arabic & Greek in my regional settings (I can write in both languages in any application)

Any idea how to solve this?