Why is an IMAP Inbox Only Displaying 10,000 Items When There are Many More Emails on the Server?

I had similar results when deleting the AOL OST. It is constantly syncing but gets nowhere other than sometimes overheating my PC (other times it shows doing it but non CPU). Less emails than the one that I didn't clear, never noticed it going back to 1000; isn't even downloading pictures (well, HTML), That PC is sitting around14K inbox messages; the other one is around 23K, I have around 60K on mail.aol.com.

So deleting the OST made it a little worse, although it seems to be doing nothing (but showing syncing). No, just checked, 13% CPU and getting hot, will have to stop it again. Neither are getting more (but new emails do show up and unlike the original 10K limit, new emails don't bump off old ones. This is not a limit, something is terribly wrong. Different numbers, not round numbers, and climbing with new mail.

After I deleted it and added it back, it downloaded less than 10K messages and showed no sync errors. I have more than 100K messages on the Yahoo Server. I need the emails from 2018 for a legal matter but the only way I can get to them is to go to Yahoo on the web with my browser. I am trying to download them to a Dell laptop/notebook. I had all the emails on my desktop a year ago but when I moved back home the computer wouldn’t boot up. I suspect the motherboard has failed or the CMOS battery needs replacing.

My inbox SHOULD BE in the 60's -- maybe 64K, not sure, and sure can't see it.

It gets to the 20's, locks up synchronizing and eventually starts over. And that's with the CPU in the teens and task manager calls its power "very high". Can be 10-20 Mbs network... until it stops building messages. CPU stays in the teens, power remains "very high", no network, and until it restarts, the message count only goes up with new mail. It just stopped this cycle at 21.119. Just a but short of ~64K or so (I can't remember and haven't seen that in a week or so).

On one PC I can't even search for flagged messages in a folder I created (the other can). How do I start a new OST (or rebuild this one)? Do I shut down outlook, delete the file, start it up, and it builds from scratch? I'd do that to the one with the messed-up folder (and the one I will decommission one of these days and reimage at WIn10). I'm going to leave outlook down and start it occasionally but this is nonsense, and I pay $30/month for premium AOL and only use the email which I've had since the mid 90's. (I do use some of the benefits which I think you only get with paid AOL. One of those is premium support -- is that a joke?)

I think I figured out the problem (and we can tell Yahoo that they're mistaken and wasting our time if they say we should go to Microsoft).

I wanted to see if there was any update on IMAP configuration (I'm on AOL, but I found Yahoo info first, and I assume it's the same for everybody).

It's at https://help.yahoo.com/kb/SLN28681.html (the page with the specs for adding "Export" to the server name).

As I'm reading it, I notice (red highlight is my emphasis) :

"Limitations for large folders - Folders containing upwards of 100 thousand or more emails may have issues downloading all the messages. To resolve this, move some of the email to a new folder in your account."

So I'm wondering: When/where did this come from? Or has it always been the case and they just decided to pull the trigger Sept. 15th, and changed IMAP configuration to "prove" that they were serious about "issues downloading"?

Of course the page doesn't have any date, so I try "View Page Source" and "Inspect", etc. but I'm not that tech savvy. However after some more searching, I find: https://archive.ph/help.yahoo.comThat has a bunch of historical screenshots of various yahoo pages, so I look for "SLN28681", and find four older versions (March '22, Dec. '21, April '21, and March '21).

They seemed identical to each other, but there was one difference between all of them, compared to the current version:

"Limitations for large folders - Folders containing upwards of 1 million or more emails will have issues downloading all the messages. To resolve this, move some of the email to a new folder in your account."

So sometime between March '22 and last week, they changed their protocol, didn't tell anybody, and completely misstated the situation (a maximum of 100,000 is quite different than "issues downloading").

Now that we know a bit more of what's going on, what do we do?

Meanwhile, after getting Outlook error when this all started that my mail file was corrupted (I've never had that before) I went through some Microsoft process of repairing/rebuilding it.

Since then, I haven't been able to delete anything in Inbox, Sent, Drafts, etc. because of error message: "The operation cannot be performed because the object has been deleted". So it thinks none of the emails exist?

If anyone has experienced something similar, or has any solutions, please advise.

Thanks

Worse than that; my old PC crashed several times, and feeling the back, it was really hot (I suspect the heat was the reason). The new PC (Win10) shows power usage in task manager, and outlook is "very high" at times. Not quite sure why -- while there is noticeable CPU usage, it's not that high. Didn't feel that one to know if it was hot, but at least the old one (Win7) gets hot and maybe can't take it.

Why all that? Because it's apparently spinning trying to sync, never gets past the low 20K's, starts over... repeatedly. Always shows synchronizing inbox.