Incomplete received header

[LuKreme]

I am getting some messages with an incomplete received header, they all seem to 
come from bronto.com:

Received: from ms045.bronto.com (unknown)
       by mail.covisp.net(Postfix 2.11.4/8.13.0) with SMTP id unknown;
       Sun, 19 Apr 2015 15:00:38 -0600
       (envelope-from <cl3q5hr7hjponyd66fmt70m4u3kvtoi...@bounce.bronto.com>)

I don't know why postfix is not generating a SMTP id or reporting the helo name 
or IP address. 

Ideas?

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