Lookup for "552 2.2.2"
This status code indicates a successful delivery or other operation. Any details are simply notes.
Basic Status Code Details (552)
Requested mail action aborted: exceeded storage allocation
Enhanced Status Code Details (2.2.2)
Mailbox full
The mailbox is full because the user has exceeded a per-mailbox administrative quota or physical capacity. The general semantics implies that the recipient can delete messages to make more space available. This code should be used as a persistent transient failure.