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

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.

It is not a "hack". Below is the Yahoo help page that documents the setup.

https://help.yahoo.com/kb/new-mail-for-desktop/download-email-yahoo-mail-third-party-sln28681.html

The problem is that the "export" server has been broken for a couple of weeks, so I am back to the regular IMAP server and the 10,000 message limit. The Yahoo support people are clueless, and I think it is time to get another letter to the Yahoo CEO and CTO to alert them to these unresolved issues.

The App Password functionality broke around the same time, so I suspect these issues might all be related.

Well, for what it's worth:

My Outlook for Mac client was operating without issue (except that Bulk never updates) until earlier today, when I installed Outlook on a second laptop to see how that behaved. Now both systems are in a loop resyncing although both appear to be getting all the messages. It's just that once they've downloaded everything, they start over. This seems like a bug in the Yahoo IMAP server telling the client that messages are new/changed (though the "read" status of individual messages seems to be preserved).

I'm not currently seeing any limit as to what's downloaded. Outlook gets all of the messages. But I wonder if my ISP is going to complain about my Internet usage.

I have switched off the second laptop and will leave the original on overnight.

Given the number of folks here that are having this or similar issues, we can only hope that Yahoo will wake up and realise they have a problem. I'd think that they'd be seeing suddenly very large outbound traffic volume and that this would get someone's attention.

Time to investigate other email providers ...

Good morning Norm

Thank you so much for your detailed email and for your research. I will pass the details of your Outlook 365 version to them.

All this info points to the same bad change in a way IMAP Servers for Yahoo and AOL handle the download, that must have been rolled gradually affecting users across the country in the last two months or so. The support people are very defensive as could be expected, but in my case it seems to have gotten escalated to their engineering team, who might be slightly more inclined to investigate rather than work off the customer response script. At least I got a case going back and forth via email, which almost never happens. Hope it does not get shut down by some overzealous manager

I don't expect them to respond before next week and will pass on more information from you at that time. Will keep you posted.

Hello MichaelTabb,

Welcome to the Microsoft community and enjoy the time you've spent sharing detailed information. I understand that the problem is that the AOL account is configured in Outlook, but the IMAP inbox only shows 10000 items. If my understanding is wrong, please correct me in the answer. I am pleased to offer you assistance on this issue.

We fully understand the inconvenience caused by the problem and that the current situation can be frustrating.

We found that AOL does have a certain limit on the number of emails in the IMAP protocol inbox, as shown in the figure below. The IMAP inbox can display up to 10,000 items.

You can also check related information on the AOL support website.

In view of your current situation, we suggest that you can disperse emails in multiple folders, and you can create subfolders yourself to store emails in different categories.

In addition, you can choose to archive your emails, you can refer to the method in this link to do so.

We need to go through a series of steps to find the true cause of the problem. If the steps above don't solve your problem, let me know and I will continue to help you with the problem.

Sincere greetings

Mavis - MSFT | Microsoft Community Support Specialist

* Beware of scammers posting fake support numbers here. »

* Please mark and vote on this answer if it helps, as it will benefit more community members who read here.