Sharing a situation faced recently where one of the application mailboxes was throwing error in deleting the processed items from Outlook.
When we tried to delete items manually thru outlook we got below error:
Some items cannot be deleted They were either moved or already deleted, or access was denied.
At first we tried cache mode & tried to delete-sync --> no Success
Tried Exchange mailbox repair options --> no Success
In the end we found that RecoverableItemsQuota is reached & thats what is causing the issue.
Either you can clear the recoverable items or you can increase the recoverable quota.
To clear the contents you can use:
Search-mailbox -identity mailbox -SearchDumpsterOnly -DeleteContent
To increase the Quota you can use:
Set-Mailbox -Identity "mailboxalias" -RecoverableItemsQuota 20Gb -RecoverableItemsWarningQuota 15Gb
Doing one of the above will resolve this issue for you.