Inferences?.xml files in Outlook folder?

Question

_{Wednesday, March 23, 2016 6:29 PM}

Does anyone have an idea what the Inferences?.xml files are that Outlook (365) started to generate some months ago in the default folder where my mailboxes are stored? 

Typical of the file names are the following:

Inferences0C9A4E96C0DA9842A75323F845899A61_{A9C46A2D-F194-4961-9A4B-BCC43786D262}.xml

It looks like a new one of these is generated every time I start Outlook, and they stay in the default folder after quitting Outlook. 

I have all sorts of (5) email accounts, but these files seem to be generated by an Exchange or Exchange Server account; my computer can connect but does not have to be connected to a domain network when these appear. 

Attached are screen shots of the types of files generated and typical content can be found in my earlier posting that did not get answered here.

Any idea?

All replies (10)

_{Wednesday, March 23, 2016 6:32 PM}

So the system won't take my link at the moment -- irritating -- but you can find it at answers-dot-Microsoft-dot-com slash en-us slash office slash forum slash office_365hp-outlook slash inferencesxml-files-in-outlook-folder slash 637f603d-3e89-4213-883f-88dcc34f1e2d?auth=1

_{Thursday, March 24, 2016 9:31 AM}

my computer can connect but does not have to be connected to a domain network when these appear. 

Would you please explain the quoted sentence so that we can understand it more clearly?

I also have the Inferences?.xml files in my environment, but I haven't noticed any issues caused by these files.

Regards,

Steve Fan
TechNet Community Support

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_{Friday, July 1, 2016 3:44 PM}

I have the Inferences?.xml files on one user in my environment who IS having problems. But I have no idea whether this is a symptom, a cause, or completely irrelevant to the problem. That's why it'd be nice to have documentation about the purpose and function of those files. This is the same folder which contains the ?-Autodiscover.xml, which is often quite useful for verifying functionality and diagnosing problems.

_{Friday, November 11, 2016 5:40 PM}

Has anyone been able to explain what these Inferences? files are yet? The Microsoft guy says " I haven't noticed any issues caused by these files" but hasn't explained what they are and why they are there?

_{Wednesday, February 8, 2017 9:09 PM}

Because of the new Outlook changes I had to build a new profile for my outlook 2016. before doing this I renamed my .ost file then deleted my profile via Control Panel/mail. I then built a new profile and opened outlook. it took a while to sync my emails, contacts and calendar. I checked the folder and a new .ost was there. After closing outlook I noticed an inference xml file had generated and does so every time I close outlook.

I would love to know what is wrong and how to stop these from generating.

Any clues?

_{Tuesday, August 29, 2017 4:50 PM | 1 vote}

Anyone able to explain the reason for these XML files being created?

The computer I have that is having Outlook issues requires 3 tries to open Outlook.

I have to launch and kill the process twice and the third time Outlook opens and works fine.

Then when I close Outlook a new "Interference?.XML" file is created each time.

Any help would be greatly appreciated.

_{Sunday, August 5, 2018 4:52 PM}

These are files that Outlook uses to keep track of data uploaded from the .ost file to Office 365. The are created when you shut down Outlook. Obviously they are not needed when Outlook 'catches up' hence you see them eventually disappear when Outlook is open long enough.

If you have ever imported a large .pst file, you can see this behavior clearly. Outlook will copy the .pst data into the .ost file; this happens quickly (generally at file copy speeds). In the background, Outlook uploads the new data to Office 365 at a background rate, which takes a long time (many hours or days).

_{Thursday, September 6, 2018 3:35 PM}

So can you safely delete these files?? Except perhaps the latest one? 

_{Friday, January 18, 2019 5:02 PM}

I just killed all of my 2018 ones( 50 or better ) and my outlook actually seems to open faster??

_{Wednesday, February 27, 2019 11:19 PM}

You can delete them, but be careful: Perhaps the upload process is not finished and without the "inferences"-files outlook stops uploading data to the exchange server. So I had the issue that on one PC I had e-mails that weren't uploaded and then of course I couldn't see them on another PC when starting Outlook there.