Volume 30 Issue 29

Issue Date: September 25, 2025 « Previous Issue | Next Issue »

The following articles were included in our Exchange Messaging Outlook (EMO) newsletter published on September 25, 2025.

EMO is a weekly publication. To receive your own copy of EMO by email, subscribe here.

Support Exchange Messaging Outlook Sponsors

Increase Your Productivity!

ReliefJet Essentials for Outlook is a set of more than 160 tools for performing a wide range of tasks in Outlook: processing email messages, contacts, appointments, meetings, tasks and other Outlook items.

ReliefJet Essentials for Outlook

Today's Highlights »

New Outlook's Temporary Attachment Folder
Classic Outlook’s Temporary Attachment Folder
Permanently switch to classic Outlook?

New Outlook's Temporary Attachment Folder

A user opened an attachment from new Outlook, edited it then saved but couldn’t find the file.

The user explained it like this: “I was working on an Excel file and thought I saved it to OneDrive but the latest version there does not have my latest edits. I found a local path for the file but when try to open the link, I receive a message that the file path is not found. When I go to the Outlook folder at C: > Users > %username% > AppData > Local > Microsoft > olk, there is nothing there.“

The path C: > Users > %username% > AppData > Local > Microsoft > Olk > Attachments > is the temporary file path for files opened, attachments sent, and some (not all) attachments received in email when you are using the new Outlook app.

The path is a hidden path, so you may not see anything browsing to the folders if you don't set File Explorer to show hidden files and folders.

Under the Attachments folder is one or more folders, with folder names beginning with ooa- and ending with a GUID. Each account in new Outlook should have an ooa- folder.

Based on what I have in my folders, Outlook doesn't clean up after itself, so it's not all that temporary (unlike classic Outlook's temp folder), but I would not trust it and use Save as to save files elsewhere.

If you are trying to open the folder, don't paste the full path - use %localappdata% then Microsoft > Olk > Attachments. Search for file extensions within the Attachments folder. All subfolders will be searched.

Not all my incoming attachments are in this attachment cache. Attachments I sent are found and text, docx, pdf, and xlsx files, but only images I sent, only a few images I received. I have 4 folders because I have 4 accounts configured in new Outlook. I did not open most of the text files in my mailbox (log files from my website backup program), but it looks like they are all in the folder.

While you shouldn’t rely on antivirus to protect you when you do dumb things, like open attachments from people you don't know, the file is written to the attachment folder before its opened so your antivirus can scan it.

Classic Outlook’s Temporary Attachment Folder

Classic Outlook has a temp attachment folder too. It’s under %localappdata% > Local > Temporary Internet Files > Content.Outlook, in folders with 8 random characters for the file name. If you close the attachment, then close the message (or switch messages) the temp file is deleted. If you open an attachment and leave it open as you read other mail, the attachment won’t be deleted from the temp cache.

Tip: you can jump to the Temporary internet folder by typing shell:cache in File Explorer’s address bar. Then select Content.Outlook (or a folder beginning with OLK if using an old version of classic Outlook.) The folders should be visible when you use shell:cache, but if not, you will need to show hidden files and folders. Temporary Word files are stored in Content.Word folder under the Temp Internet folder.

Classic Outlook’s cache folder can be moved by editing a registry key.

I have more information and the registry key to move the folder in my article at Outlook SecureTemp Files Folder

Permanently switch to classic Outlook?

While you can turn off the switch to use new Outlook, to completely block getting switch back to it, you need to set a registry key. And note, this is only "permanent" until 2029.

If the switch in in upper right corner of new Outlook is turned on, slide it off. This should return classic Outlook’s icon to open classic Outlook.

If the New Outlook switch is missing, look on the Help menu to revert to classic Outlook.

If you are using a new computer, you may need to install classic Outlook. Type Outlook on the start menu – do two Outlook icons come up? If not, install classic from this link: Install or reinstall classic Outlook on a Windows PC

Note: you need an Office subscription to use the Outlook download.

Next set a registry key to hide the Try new Outlook toggle in classic Outlook. This will prevent Microsoft from automatically turning the “Try new Outlook” switch on.

I have the registry key and instructions at Use Classic Outlook, not New Outlook. Or download and run this reg file: HideNewOutlookToggle.reg

You need to restart Outlook after setting the key.