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Some of our users been reporting that all old calendar items have disappeared from their calendar folder. All they see are the recurring appointments. All of the appointments and events that they had prior to 11/2019 have disappeared. The users have never archived their mail or calendar items before, and both of the archive settings are turned off. I'm guessing there is no way to get users' old appointments back but is there some way to know what's causing it and prevent this issue from happening again?
Our Exchange servers are currently running Exchange 2016 Enterprise with CU17 and most of our users are using Outlook 2016 in a VDI environment.
Thank you,
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Can they see those appointments in OWA?
Run Search-Mailbox for them to check if the items exist.
Also, check the retention policy assigned to them, the Default Policy Tag applies to all items in mailbox without a tag, which might be the cause.
If the tag is set to "Delete and allow recovery", you can try finding the items in Recoverable Items folder .
Besides, to check the retention dates for existing items, use MFC Mapi and follow this blog: https://answers.microsoft.com/en-us/msoffice/forum/msoffice_o365admin-mso_exchon-mso_o365b/how-and-what-to-check-when-your-emails-are-not/e9087576-fe91-4809-87fc-fff8cbb17c6a
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Hi Eric,
I ran eDiscovery to check and verify that the items are no longer exist and none of the missing items are found in the Recoverable Items folder. Also, we have an RPT with a retention period unlimited (never delete) retention tag explicitly applied to the calendar folder for the users.
Using MFC MapI, I checked the PR_RETENTION_PERIOD value on the calendar folder and confirm that the value of this property is 0 which means the object never expires. Also, existing items under the calendar has no retention dates property assigned to them.
Thanks,
Check to see if somehow the managed folder assistant did process these. Are you sure they werent exported by Outlook to a pst?
https://office365itpros.com/2018/12/10/reporting-the-managed-folder-assistant/
Then it's hard for us to track those disappeared items, I suggest to enable Mailbox audit logging for them, which could record who/when deletes something from the mailbox in the future :https://learn.microsoft.com/en-us/exchange/policy-and-compliance/mailbox-audit-logging/mailbox-audit-logging?view=exchserver-2016
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I checked but couldn't find anything that they were exported by Outlook to a pst. Our users are on a none persistent desktop and the only place they can save/export a pst file would be their home drive but no pst files were found in the affected user's home drive.
Thanks,
Did you check the MFA logging to see if that was processing anything?
Yeah, I also have the script and ran it against the user but it was no help since the MFA logging only shows the last process time and number of items deleted by MFA. The problem is that we don't know when the user's old calendar items were disappeared.
Hi Eric,
What are the reasons that old calendar items have disappeared from the users' mailbox? It appears the only way to find out is by enabling the Mailbox audit logging for the users.
Thanks,
Apart from deleting by mistake/ retention policy/Auto archive , another reason I can think of is sync issue by mobile App (especially on IOS device).
Besides, though you have mentioned in description, still want you to check:
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Hi Eric,
Can you kindly elaborate a little more on "sync issue by mobile App (especially on IOS device)" please?
I checked the AutoArchive settings in the user's Outlook and verified that it's not enabled.
Thank you,
It's just my personal guess.
We have met some issues that IOS users' mailboxes get corrupted by some Apps, which leads to calendar missing/cannot be deleted/is somehow showing twice.
Anyway, the missing calendar items your mentioned are hard to track now. You might need to backup their pst files every week to avoid such issues.
Also enable mailbox audit log to check if someone delete it by mistake.
I am writing here to confirm with you how the thing going now?
If you need further help, please provide more detailed information, so that we can give more appropriate suggestions.
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