Yahoo! Mail IMAP Download Limit Issue04 Mar 2023
I recently realised that Mail.app on my Mac doesn't show more than 10000 messages in Yahoo! Inbox. I thought, it could be issue with Mail.app, and I configued Thunderbird to download Yahoo! mails, and even Thunderbird couldn't download more than 10000 messages.
I searched around to learn if YahoO! has changed something; indeed they have. It seems with their regular two-way sync IMAP you can only download 10000 messages in Inbox (or per folder) using third-party mail software (Mail.app, Thunderbird, etc.).
Yahoo! provides a way to export messages (one way) via a different IMAP.
We need to change the IMAP server to export.imap.mail.yahoo.com; and we can download all messages. You can learn more about this here.