I did a search and found this link on reddit. Not sure if it will help.

https://www.reddit.com/r/FacebookAds/comments/1i06ljj/anyone_receives_message_from_meta_using/

I think I've been going about it "opposite". I've been enlarging the book by adding pages when the book might need to be shrunk. That's my new theory and it explains why it hasn't worked. But I've submitted it about 7 times now. So I'm gonna try the opposite and cut pages.

I'll consider your idea too, Lynn. Thanks!

Now there is a free piano scam.

I received one a while back and thought it odd.  I kind of thought it was a scam but, as I don't need a piano, I ignored it as it didn't matter either way.

Now I am getting more and more of these eMails, so it seems logical to conclude it's a scam because there can't be this many people with pianos to give away that are eMailing random strangers to see if they want them.

But what's the scam?

Well, they will ask you to pay for the moving company to move it except, reportedly, the moving company is fake so they'll take your money and you'll never get a piano.

I wonder what happens if you offer to pick it up?    (Yeah, I know, you'll never hear from them again . . .)

Maybe the last bounce?:

FinCEN Removes Beneficial Ownership Reporting Requirements for U.S. Companies and U.S. Persons, Sets New Deadlines for Foreign Companies
March 21, 2025

"...the Financial Crimes Enforcement Network (FinCEN) is issuing an interim final rule that removes the requirement for U.S. companies and U.S. persons to report beneficial ownership information (BOI) to FinCEN under the Corporate Transparency Act....FinCEN revises the definition of 'reporting company' in its implementing regulations to mean only those entities that are formed under the law of a foreign country and that have registered to do business in any U.S. State or Tribal jurisdiction..."

https://fincen.gov/news/news-releases/fincen-removes-beneficial-ownership-reporting-requirements-us-companies-and-us

As a matter of fact, Jeff just said he was.

There might come a time, however, when Substack cracks down on that. They have explicit language in their TOS that states a Substack account can't be used only for promoting another business. Whether they would regard an author who used the email feature but never posts to Substack as falling in that category, I don't know, but it does seem to be at least a possibility.

As far as writing shorts are concerned, if you already blog, you might consider testing to see if posting the same material on Substack attracts an audience there. I know at least a few authors who have an active external blog but find it worthwhile to post the same material on Substack. My experience is that such material typically gets more views.

If you don't currently blog, you might considering publishing your WIP, one chapter or so at a time. I've tried that, thinking I would hate it, and it's working out OK so far. That creates no additional work, since it's writing I'd do, anyway. It does move the work around a little. I spend more time editing prior to posting on Substack than I would on a first draft, but I figure that's just a different workflow, not a longer one.

As far as shorts are concerned, I stopped writing them when they stopped getting sales on Amazon, but I have written some for Substack, with good results. I like what I've produced, and it's pulled in new readers. I've also had success with serials (end product approximately novella length. I tie them into one of my existing series, which gives me a good way to draw Substack readers into my backlist. That also works for me, though it does create extra work. But as with the shorts, I'm liking the material I produce.

Teasers also get a surprisingly good reception.

To go back to the actual topic, posting on Substack periodically would be a way to avoid a possible future crackdown that could come from just using it as an email service. Whether or not it's worth it will depend on your individual   business plan and the time you have available. Full disclosure--I still have my Mailerlite list. I tried to nudge them over to Substack and didn't get many takers. There will be some people who will sign up for my list who are averse to being connected to an entire ecosystem.