Google Message Security Batch Reference Guide - Manual (Page 352)

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Description
This field holds the disposition for a valid or spam NDR inbound message based
on the null sender address in the envelope’s FROM field.The NDR filter does not
block NDRs with a sender address. An example of a valid NDR message is, after
sending mail to someone’s who is out of the office, your mail server receives an
auto-reply vacation report. If your domain has been used in the FROM field of a
spammer’s mail (spoofed), your mail server receives a NDR report if the mail was
sent to a non-existing recipient.
The NDR filtering dispositions include:
• quarantine -- Insert the message into the recipient’s quarantine. These
messages appear in the user’s Message Center or Quarantine Summary with
the a blank in the filter column.
• blackhole - Silently discard the message.
• <“errstr”> -- Bounce the SMTP request with the error code + custom error
string. The error string must be a syntactically correct RFC 821 response
string. This is the same as the ERROR <“errstr”> but, in some instances,
more convenient.
The field accepts 4xx and 5xx error codes. The messages with 4xx error
codes will be continuously rejected. The practical error codes are the 5xx
codes. The messages with 5xx codes are permanently rejected.
• ERROR <“errstr”> -- Bounce a SMTP request with the error string response.
The error string must be a syntactically correct RFC 821 response string. The
addorg and modifyorg commands return an error for ill-formatted syntax.
The error string is returned to the address in the Return-Path or the SMTP
envelope sender address FROM: field.
• NULL -- This field is not active.
Default: NULL
Field Type
Org-level
Authorization
• Read: Edit organizations
• Write: Edit organizations