Lookup for "250 2.2.4"
This status code indicates a successful delivery or other operation. Any details are simply notes.
Basic Status Code Details (250)
Requested mail action okay, completed
Enhanced Status Code Details (2.2.4)
Mailing list expansion problem
The mailbox is a mailing list address and the mailing list was unable to be expanded. This code may represent a permanent failure or a persistent transient failure.