What are the _0 folders in the new Outlook 365?

It contains all sent email from 2001 - 2021. My regular sent has everything from September '25 forward. So everything from 2021 - 2025 seems to be missing. It also has sent mail from my son, who had a "sub account" under my original Xfinity, when it was home.com, which then became attbi.com, which then became comcast.net. I don't think any of that info is relevant but it is an indication that the current Xfinity does have ALL my "account" email going back 25 years, and something inexplicable has happened, either because of Microsoft changes or Xfinity issues. I am just trying to hunt it down.

Thanks for sharing the details. What probably happened is that New Outlook recognized multiple older “Sent” folder structures from the different account periods (home.com, attbi.com, comcast.net, subaccounts, etc.) and, rather than merging everything automatically, it created Sent Items_0 to keep the older emails separate.

The good news is that your older emails are still intact and haven’t been deleted by Outlook.

Could you try logging into your Xfinity Webmail directly in a browser to check a few things?

• Are the missing 2021–2025 sent emails visible there? • Do you see multiple Sent folders? • Are there folders named “Sent”, “Sent Messages”, or any other duplicates besides “Sent Items”?

When I log into my web mail there is another folder structure underneath the main folder structure called My Folders. It has subfolders of Deleted Items, Junk Mail and Sent Mail. The first two are empty. The Sent Mail has mails supposedly starting in 2021, but the top of the list contains a number of emails all dated 1/18/2021 that are incorrectly dated. The top of the list contains mails from my son's account on the old mediaone (which was gone way before 1/18/2021) and then some from my account at attbi.com that are also incorrectly dated and then some from home.com with the same incorrect 1/18/2021 date, and then suddenly goes to a 9/7/2020 date, which is correct and is my current jleo2 account. It continues to go back from there (I am sorting in reverse order) and I am guessing it goes back to around 2001, where those 1/18/2021 mails originated from, but I have to do it a page at a time online and it is cumbersome. So this one has all the sent emails up to the 9/7/2020 and the incorrectly dated "problem" emails from the old domains that may have triggered the problem. I hope this makes sense. The missing 2021-2025 mails are not in either folder.