Email sent to and Exchange online resource is being auto-deleted.


First, we're in a hybrid environment and have been that way for a few years.  Everything has worked great, until about a month ago. At that time, email sent to resources started being auto-deleted.  Calendar meeting requests still work fine, but messages sent to the resources are being deleted.  This is not happening to all resources (yet), only a few.  Has anything changed in Office 365 to cause this change in behavior?


4 Replies

It's an option of the resource mailbox:


Set-CalendarProcessing roommailbox -DeleteNonCalendarItems $false


For more info refer to the cmdlet help:


In addition, you might want to check for rules, both Inbox and Transport ones.



Thank you for the script.  But, within 24 hours of my posting, everything started working as normal. Makes me think Microsoft did something on the backend.



@Vasil Michev Thanks a lot mate! You saved me some precious time. Cheers

Hello, @Paul Long, here you can find the steps to solve your problem: 

$LiveCred = Get-Credential 

Used Office 365 global admin credentials

$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri -Credential $LiveCred -Authentication Basic -AllowRedirection
Import-PSSession $Session
Set-CalendarProcessing roommailbox -DeleteNonCalendarItems $false

If this does not work, you should understand that numerous factors can lead to emails being deleted automatically. Try to consider these cases:


Check if any email rule causes deleting the emails. Hit Home > Rules > Manage Rules & Alerts to view the list of rules. If such rules exist, please uncheck the rule or remove it as you need.


Check if the internal domain is not blocking the emails. Hit Home > Junk > Junk E-mail Options, enable Blocked Senders tab in the popping dialog, and check whether your internal domain exists or not. If exist, please remove it.


Check if emails from the internal domain are not filtered. Select the Inbox folder, click View > View Settings > Filter, and check if there are filter criteria to hide internal emails. If exist, please remove it. Or just click the Clear All button to remove all filter criteria.


Another suggestion is to have Outlook and Microsoft 365 backup for cases of unpredictable situations such as ransomware issues. Check this document.