Some of the greasy IRS scammers have caught on to the fact that the IRS uses the US mail. They're trying to skirt this fact by claiming that mail has been sent. What the mental midgets can't get around is the fact that the IRS does NOT make threats of any kind over the 'phone & NEVER demands immediate payment by 'phone.
The IRS does NOT make threats of lawsuits or charges of fraud by 'phone. Particularly NOT with a recording! The reason that the frauds used this method is that they're hoping to "soften up" the target. Another call will come & I can guarantee that the caller will have an Indian accent. When the caller is questioned, or outright called a scammer, he/she will become verbally abusive & probably obscene. Thereby giving themselves away.
The foreign frauds running this scam are very dim-witted. Use that against them. Ignore the calls and/or block them.
Be Safe. Be Aware.
Gunnar