For Outlook.com/Hotmail, this behavior is commonly seen when a large number of messages are being deleted at once.
Try this sequence:
- Open the folder being cleaned up.
- Delete a smaller batch instead of 10 or more messages.
- If the messages move slowly or the page appears stuck, leave the browser window open for a while before refreshing.
- If deleting still fails, open Deleted Items and select Empty.
- Then select Recover items deleted from this folder at the top of the page and select Empty folder again.
Important details:
- If a lot of email was deleted recently, it can take time for items to move to or be removed from Deleted Items.
- If email still fails to delete properly, use a smaller batch.
- If deleted email comes back, try again later.
- If Focused Inbox is enabled, Focused and Other inboxes must be emptied separately.
- On mobile browsers, press and hold a message, tap Select All, then use the trash icon.
If the issue is in classic Outlook for Windows with a POP account using Download Headers Only, there was a known crash when deleting 3 or more emails in Outlook for Microsoft 365 version 2006 build 13001.20266 and higher. That issue was fixed in Current Channel Version 2009 Build 13231.20262. In that case, update Outlook from File > Office Account > Update Options > Update Now.
The Yahoo portion is not covered here.
References: