How to turn OFF "Improper folded header field made up entirely of whitespace"

[Mike Schleif]

postfix 2.10.1

How can I turn OFF the following particular header check ONLY for outgoing
email?
    "Improper folded header field made up entirely of whitespace"

We're using postfix between the internet and MS Exchange 2010, and MS
Outlook 2010 MUA.

Several times per week, outgoing mail is quarantined for this header
violation, always in the References: header, example below:

...
References: <
BY1PR13MB0151F1E18A901505CAE7F071CC710 at BY1PR13MB0151.namprd13.prod.outlook.com
>
 <1F13EA4287F2B24EA0E390BCFD313E7AB8A51E8D at SemExchange.sempris.local>
 <
BY1PR13MB01510E8FAC2AA3D5241F8BD4CC710 at BY1PR13MB0151.namprd13.prod.outlook.com
>

Accept-Language: en-US
...

We do not want to turn header checks off completely. Incoming email is not
a problem for us.

For internal automated emails from legacy systems, we have already
implemented:
  $interface_policy{'10027'}   = 'SENDERBYPASS';
  $policy_bank{'SENDERBYPASS'} = {
    bypass_header_checks_maps  => [1],
    final_bad_header_destiny   => D_PASS,
   ... }
via: /etc/postfix/amavis_sender_bypass

How can we turn OFF only this one header check for all outbound email?
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