Lookup for "214 2.7.5"
This status code indicates a successful delivery or other operation. Any details are simply notes.
Basic Status Code Details (214)
Help message [Information on how to use the receiver or the meaning of a particular non-standard command; this reply is useful only to the human user]
Enhanced Status Code Details (2.7.5)
Cryptographic failure
A transport system otherwise authorized to validate or decrypt a message in transport was unable to do so because necessary information such as key was not available or such information was invalid.