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

The cycling occurs with Outlook/AOL export server and Outlook/AOL original imap server and Mailbird/AOL export server and Mailbird/AOL original imap server.

In all four of these combinations, the behavior of the cycling appears to be identical.

I can't address Mailbird other than to ask how current is it? For outlook I'll ask, what version (if Office365 is it at least relatively current (my Outlook 2019 can't be that new although it has had upgrades)? And what Windows (if it is Windows)? The bad one for me is old on both counts, although I'm not positive the newer ones don't cycle (faster PC, so smaller window to discover it cycling).

And didn't mention, but even if it doesn't fix the cycling, there is another advantage of the "export." URL -- it can at least have folders with more than 10K messages.

I switched from TBird to Outlook 365 in early February (around Feb 3). The "cycling" of going down to 1000 messages in the Inbox and Sent folders then "re-retrieving" the emails back to 27K (Inbox) and 8K (Sent) caused my Xfinity data usage to increase from less than 300GB/month to 1.6TB for February. I'm at 700GB for March. Fortunately, Xfinity will "forgive" the first time you exceed the 1.2TB/month limit, so I didn't get charged extra for February. To keep from getting charged going forward, I switched to Xfinity's unlimited plan, which costs me an additional $25/month. So now, this issue is costing me real money.

After using my AOL Mail email address since 1990, I think I'm going to take this as a sign that I need to change email addresses and move away from AOL Mail over the next twelve months.

Wow, and I thought it was just an annoyance, possibly overheating my PC, but that is a direct cost of that. I forgot that some people have metered or at least capped data.

You also seem to show that it's not Microsoft since my Outlook 2016 cycles but I haven't noticed Outlook 2019... although they're also on WIn7 and Win10 respectively. (Unless Office365 hasn't been updated in years.)

I have an IMAP email account that is hosted by AOL Mail, which I download into Outlook 365. The AOL Account has emails going as far back as 2015, and until recently all of those emails were visible (and searchable) through Outlook. About 2 weeks ago, I noticed that I could no longer search for emails going back farther than 6 months ago. Those emails are still on the AOL server; I can see them if I use AOL's webmail interface (which is pretty mediocre). But they are no longer downloading into my IMAP inbox. Indeed, at the bottom of the inbox it now says I have 10,000 items.

That's the maximum. If I delete say 100 emails, another 100 emails will download from the AOL server but the downloading will stop when I hit 10,000. (When new emails download from the account, older emails are deleted so I'm just about always at 10,000 items). The full set of emails remains on the AOL server.

In my IMAP Account Settings for this email account, I have the "Keep Mail offline" setting pushed all the way to the right at "All".

I can't find any setting in Outlook that limits the number of emails. Nor does there appear to be any setting in the AOL account that limits 3rd party IMAP mailboxes to only 10,000 items (at least not one that I can find). New emails are downloading and syncing with the AOL server, so my connection settings appear to be correct.

Is there some kind of Registry setting that is limiting the number of items that will load into this email inbox? I used to have access to all of the emails that were on the AOL server. Is there any way to get that back?

One last note. I deleted the AOL account from Inbox, rebooted and then reinstalled the AOL account. It still only downloaded 10,000 items in the IMAP inbox. Also I'm using the most recent version of Outlook 365.

Thanks for any help anyone can provide.

I am facing exact same problem that is mentioned above for Outlook 365 with all updates as of 07-July-2023. Only 10000 emails in Outlook Inbox when I configured the mailbox today.

However, for a slightly different perspective to the above problem, I am also using MailStore Home Free Portable for taking a backup of my Yahoo email using IMAP and although MailStore Home Free Portable is not an email client by itself, it does download all emails from Yahoo servers for all folders, indexes the emails and attachments too. I do this regularly every few weeks to have all the latest emails too. This works fine. When I search for the oldest email from 2000 available on Yahoo server in the offline archive, it is there and I can find it in seconds using the Search functionality of MailStore Home Free Portable

So, I personally feel that it could not be Yahoo IMAP Servers or the other IMAP servers that could be limiting to 10000 emails. It appears certainly something in Outlook 365 that is limiting the emails to 10000.

One other thing that is possible and mentioned somewhere in this discussion earlier, MailStore Home Free Portable must be resending requests for next 10000 and and hence, it is able to get all emails whereas Outlook 365 may not be sending the requests appropriately. I am just guessing as I am not an expert on IMAP protocol or commands. One response before also confirmed using OpenSSL connection to Yahoo IMAP server that 10000 is indeed somewhere in the request.

As a suggestion, I will also urge others to also take an offline backup of their emails using any software of their liking.

e.g. In my case, I am leaving ALL emails in all folders intact on the Yahoo email servers at the same time having an offline backup of them all.

p.s. If I use export.imap.mail.yahoo.com instead of the normal imap.mail.yahoo.com to retrieve all emails from Yahoo mail servers, it seems to be working as Outlook 365 has started getting more items from the Inbox now.

The count is increasing from 10000 now.

I did some testing via imap to understand difference between imap.mail.yahoo.com and export.imap.mail.yahoo.com and discovered the following:

If I use export.imap.mail.yahoo.com instead of the normal imap.mail.yahoo.com to retrieve all emails from Yahoo mail servers, it seems to be working as Outlook 365 has started getting more items from the Inbox now.

The count is increasing from 10000 now.