Automatically archiving all emails older than 30 days from the Deleted Items folder in the Exchange Online mailbox?

Hi @EnterpriseArchitect ，

What is the procedure for automatically archiving all emails older than 30 days in the Deleted Items folder in a mailbox with an Exchange Online P2 license?

If you want to archive the old items into a local PST file, please make sure your archive mailbox is not enabled so that you can see the AutoArchive option available in Outlook client. And then you can follow the basic steps below:

Step1: Configure the global auto archive setting for your mailbox via File > Options > Advanced > AutoArchive > AutoArchive Settings...

Step2: In the Navigation Pane's folder list, right-click the Deleted Items folder, and click Properties, on the AutoArchive tab, select the option "Archive items in this folder using the default settings".

Note: also go through the Properties for every other folder (switch to Folder view) and make sure they are configured as "Do not archive items in this folder".

Step3: To run the autoarchive now, you can go to File > Tools > Clean Up Old Items... , select Archive all folders according to their AutoArchive settings:

Reference: Archive older items automatically.

If you are interested in doing it from the perspective of Exchange administrator, you can enable the archive mailbox for the affected users and configure the retention policy for them based on your need.

Detailed instructions, hopefully you can find the article below helpful:
Customize an archive and deletion policy for mailboxes in your organization

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