DSN

gem 'dsn'

dsn = DSN.new('5.7.5')
dsn.valid?
# => true
dsn.success?
# => false
dsn.transient_failure?
# => false
dsn.failed?
# => true
dsn.to_s
# => "5.7.5"
dsn.subcode.to_s
# => "X.7.5"

dsn = DSN.new('5.7.999')
dsn.valid?
# => false
dsn.class_subcode.valid?
# => true
dsn.subject_subcode.valid?
# => true
dsn.detail_subcode.valid?
# => false
dsn.to_s
# => "5.7.999"
dsn.subcode.to_s
# => "X.7.XXX"

msg = DSN::Message.new(dsn.subcode)
msg.summary
# => "Security or Policy Status"
msg.body
# => "The security or policy status codes report failures involving policies such as per-recipient or per-host filtering and cryptographic operations.  Security and policy status issues are assumed to be under the control of either or both the sender and recipient.  Both the sender and recipient must permit the exchange of messages and arrange the exchange of necessary keys and certificates for cryptographic operations."

DSN.message('5.7.5').summary
# => "Cryptographic failure"