Part of the message, which was not signed, reads: Romney's 1040 tax returns were taken from the PWC office 8/25/2012 by gaining access to the third floor via a gentleman working on the 3rd floor of the building. Once on the 3rd floor, the team moved down the stairs to the 2nd floor and setup shop in an empty office room. During the night, suite 260 was entered, and all available 1040 tax forms for Romney were copied. A package was sent to the PWC on suite 260 with a flash drive containing a copy of the 1040 files, plus copies were sent to the Democratic office in the county and copies were sent to the GOP office in the county at the beginning of the week also containing flash drives with copies of Romney's tax returns before 2010. A scanned signature image for Mitt Romney from the 1040 forms were scanned and included with the packages, taken from earlier 1040 tax forms gathered and stored on the flash drives.
Feds probe alleged hacking theft of Romney's tax returns
Every source I've found thinks it's a hoax.