Lookup for "502 2.2.3"
This status code indicates a successful delivery or other operation. Any details are simply notes.
Basic Status Code Details (502)
Command not implemented
Enhanced Status Code Details (2.2.3)
Message length exceeds administrative limit
A per-mailbox administrative message length limit has been exceeded. This status code should be used when the per-mailbox message length limit is less than the general system limit. This code should be used as a permanent failure.