We have a common mailbox setup that receives quarantined spam messages. We want them deleted after so many days. How can we do that in Exchange 2013 automatically/on a schedule?

Thank you!

You're welcome to read up on Mailbox Records Management.

https://technet.microsoft.com/en-us/library/dd335093%28v=exchg.150%29.aspx?f=255&MSPPError=-2147217396

Hi,

According to your description, you want to remove the Spam messages.

On exchange 2013, you can create the retention policy for the mailbox.

To apply one or more retention tags to a mailbox, we can add them to a retention policy and then apply the policy to mailboxes.

More detailed information, please refer to the below link:

https://technet.microsoft.com/en-us/library/dd297955(v=exchg.150).aspx  

Regards,

David