See also, Async_bounce, Syntax – Google Message Security Batch Reference Guide User Manual
Page 299: Examples, Description, Field type

Batch Organization Fields
311
See Also
Editing Message Archiving Settings
async_bounce
The async_bounce field lists whether the Connection Manager’s Asynchronous
Bouncing control is activated for inbound traffic. This control is for email servers
that issue “unknown user” bounce messages asynchronously and require added
security.
This field is applicable to the Google Message Security, Google Message
Discovery, and Google Message Filtering products only.
Syntax
async_bounce=on | off | NULL ()
Examples
•
When the field is returned as output:
async_bounce NULL()
•
To turn the feature on:
modifyorg sales, async_bounce=on
Description
Used for email servers such as Microsoft Exchange and qmail that accept
inbound mail before validating and possibly sending a bounced “unknown user”
reply.
•
on -- By activating this feature, the Message Security service will compare
directory information with incoming recipients to measure erroneous delivery
attempts.
•
off -- Turns this feature off for the org.
•
NULL ()-- This field is not active.
Field Type
Org-level