Microsoft admits Outlook problem: email cannot be sent if there are more than 500 nested folders

CTOnews.com, December 9 (Xinhua)-- Microsoft issued an announcement on Friday acknowledging that Outlook problems reported by Microsoft 365 users could prevent email from being sent properly due to too many nested folders.

CTOnews.com translated part of the Microsoft announcement as follows: "when Microsoft 365 users use desktop-side Outlook to send email, they may accidentally pop up a non-delivery report (NDR) with the error code 0x80040305."

This problem is the same as the 500 folder limit previously fixed by Microsoft, if the number of folders containing subfolders exceeds 500, it may prevent mail from being sent.

Microsoft recommends that the number of folders containing subfolders be reduced to less than 500, with a maximum of 450 folders nested during the ongoing investigation of this issue.

Another temporary workaround is to keep all mailbox folders collapsed rather than expanded.