Hi Michael,
I've looked into the whole thread. I understand that you’ve applied a Never-delete retention policy to the shared mailbox. However, it doesn't seem to work, which is an abnormal behavior.
To narrow down the root cause of the issue, I’d like to confirm some more details:
1. Does it occur in other shared mailboxes?
2. Are they deleted periodically? If not, they might be deleted by someone who has admin role to the shared mailbox.
Here are some suggestions for your reference. Please try them to see if they help.
1. Please check the Autoarchive feature of Outlook client in which this shared mailbox is set up. It’s turned off by default. If this feature is turned on, emails will be moved to this local computer without leaving a copy in the cloud.
I've looked into the whole thread. I understand that you’ve applied a Never-delete retention policy to the shared mailbox. However, it doesn't seem to work, which is an abnormal behavior.
To narrow down the root cause of the issue, I’d like to confirm some more details:
1. Does it occur in other shared mailboxes?
2. Are they deleted periodically? If not, they might be deleted by someone who has admin role to the shared mailbox.
Here are some suggestions for your reference. Please try them to see if they help.
1. Please check the Autoarchive feature of Outlook client in which this shared mailbox is set up. It’s turned off by default. If this feature is turned on, emails will be moved to this local computer without leaving a copy in the cloud.
2. Set In-Place Hold to the shared mailbox. After that, you can create granular hold policies to preserve mailbox items such as indefinite hold. The indefinite hold scenario is similar to litigation hold in Exchange 2010. It’s intended to preserve mailbox items so you can meet eDiscovery requirements. During the period of litigation or investigation, items won’t be deleted.
We can find them using eDicovery.
3. Forward all those emails to other mailboxes or shared mailboxes using inbox rules or transport rules.
Please feel free to let me know the result after trying the suggestions above.
Thanks,
Bernny Sun