The IRS sends out "notification of law letters" that basically the say the same thing. The IRS also does "knock and talks" where they go visit the customer to discuss it personally. However, I've never heard of DOJ doing it. Since they have sworn off just confiscating customer funds for structuring in the absence of other criminal activity, maybe they have moved to a letter writing campaign?
In essence, your bank has been "outed" for filing the SAR as there is no one else who might possibly be familiar with your customer's cash activity.
Train your employees using
this video, but get a copy of the letter and write to the author expressing any opinion you might have of the practice. Copy your Congressional representatives.
This is not a recent development. See
Post 738340 in this thread from 2007.