Dumaru is about 2 or 3 weeks old. Symantec added it to its virus definitions within a couple of days. Any virus whose name begins "W32" is by definition Windows-based, and do not affect Macs (except for rare viruses designed to compromise either Mac or PC systems).
You should be aware the e-mail's originating address is probably meaningless. It is common for the address to be fake ("spoofed").