I've received an email from the REAL Feds once. They emailed me once (regarding investments) to tell me that they're sending me a letter informing me that I'm under investigation and have been for months.
The email had a PDF of the letter that I was to expect and it had all of their contact information and asked me to contact them.
At the end of the whole debacle it turns out it was sparked by a fraudulent complaint over a matter that regulators take very seriously and that's the last I've heard of them. They certainly don't tell you to have a nice fucking day or that they'll be getting to you in a week or what laws you've broken over email. LMAO
Damn, trolls are getting lonely.