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.

Yep. Scraped maybe half of mine going back ten years.

I don't know. I've reset the sizes and re-published over 5 times now. I'll try a couple more and, probably, throw in Gregg's advice of ^^ contacting them. I'll fix it somehow. Thanks!

No, there's no change with the cover. I'm thinking maybe it's a change in the computer algos since the book was published 3 yrs ago?
edit} I should add, the hardcover with the adapted hardcover from 3yrs back worked fine. It's really odd.

I recently changed my company imprint name and address. So my paperback was changed with just the title information. Now Amazon says the spine:
"Reduce the size of your spine text in your cover file. Spine text needs at least 0.0625" (1.6 mm) space on either side so that it doesn't wrap onto the front or back cover"

But it's the same cover???

I tried to increase the size of the book by 10 pages. That didn't work. Does the actual cover need to be altered? And why was it accepted before?

I would call them and tell them it's the same cover. See what they say.