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

Just got another response from Yahoo, which would be valid for AOL too, I guess

Thank you for contacting Yahoo Support.According to our engineer team, depending on the version of Outlook that you're using, there may appear an issue with the third party app which doesn’t support our advanced IMAP implementationCould you please let me know the version of Outlook that you're using?

This is exactly what I suspected

Can I ask people to please reply with their Outlook versions, so that I can demonstrate to Yahoo that their 'implementation' is bad for all versions of Outlook?

Hello All,

The solution was posted elsewhere today. Here is the link:

I have executed this solution on Outlook 365, iPhone, and Macbook

Is there an approval process still ongoing w/ regard to the limiter?

https://twitter.com/andrisreinman?lang=en

Jun 10 The new Yahoo IMAP server also uses the yet-not-approved IMAP extension MESSAGELIMIT https://ietf.org/id/draft-ietf-extra-imap-partial-01.html So people with large mailboxes have issues running FETCH 1:* queries as it would return a NO 🤔

It also seems that Yahoo now forcibly invalidates the IMAP session after 1 hour. C: X IDLE S: + idling ... some time passes, until 1h since login ... S: X NO [AUTHENTICATIONFAILED] IDLE Invalid credentials

8. Acknowledgments

This document was motivated by Yahoo! team and their questions about best client practices for dealing with large mailboxes.

I have the same problem with a Yahoo email account. Upon debug it is definitely a server problem.

I used OpenSSL to directly access the Yahoo IMAP server so that I could see the responses generated by the Server. There is an IMAP command that queries the number of messages in a folder. The response returned by that query is 10000. I am certain that my Inbox has more than 10000 messages because I can still view the older messages using the Web based mail interface. So the server is returning a response that is incorrect and this cannot be blamed on the client.

In detail the commands used to recreate the behavior are as follows (running from a Ubuntu shell from Windows Subsystem for Linux)

% openssl s_client -crlf -connect imap.mail.yahoo.com:993

tag login <email_address> <secure_mail_key>

tag SELECT Inbox

tag STATUS Inbox (MESSAGES)

tag logout

and the response to the penultimate command is

* STATUS "Inbox" (MESSAGES 10000)

tag OK STATUS completed

Note that <secure_mail_key> is not the email account password but is the randomly generated App mail password that can be generated from Yahoo mail account settings.

Thanks for all your work, Yan. Starting a few days ago, I had the identical problem as everybody else (mine was AOL). Deleted and reinstalled, same 10,000 max for Inbox and Sent.

I use Office 365 from work and I hope this is the version info you need:

Microsoft® Outlook® for Microsoft 365 MSO (Version 2205 Build 16.0.15225.20172) 64-bit .

Also, maybe you can convince Yahoo if you tell them that it's not only Outlook but Apple as well !!

I found the following complaints from Mac users having the same issues with both AOL and Yahoo!! :

https://discussions.apple.com/thread/253810183https://discussions.apple.com/thread/253646691

I wanted to respond, but don't have an Apple ID.

I called AOL and the rep saw I had 70,000 emails on the server going back 20 years. He went to a Supervisor who said that the 10,000 must be my number of Unread emails. He then remoted in to my machine so he could verify that the older emails were actually missing.

I told him about response you got re: "advanced IMAP implementation", and of course he said that it must relate solely to Yahoo, insisting that AOL didn't make any such change.

He concluded that there was nothing AOL could do because since my old emails were still on the server, it must be an Outlook problem.

I literally read him some of the Mac users' posts, and he told me that it wasn't my place to report or solve other User's problems, only mine. They should contact Apple, and I should check with Microsoft.

I pointed out that it was HIGHLY unlikely Apple AND Microsoft would change their IMAP protocols within days of each other and "coordinate" to both create this 10,000 limit, and he said that if there was that kind of major problem, AOL would have issued an internal "Bulletin" about it.

If more people called in, he thought maybe AOL might become aware of it, but without a Bulletin, there was nothing he could do.

So let's all "pound Yahoo/AOL", as you suggested in your first post.