Occasional errors sending email through RT: Duplicate header field

Hello!

    I'm using RT 4.4.1 sitting behind Kolab 16 as a mail server. This 
includes amavisd-new as a filter, and this combination causes bounces to 
RT occasionally... and my customers aren't getting my replies!

    If I send an email to an RT ticket, which I am the owner of, RT 
sends an email on my behalf to the requestor (as it should). 
Unfortunately, amavisd-new sometimes sees 2 "Sender" headers and rejects 
the email which creates a new ticket in RT with the bounce reason. Here' 
the header-1.hdr attachment that amavis replies with:

    Return-Path: <[email protected]>
    Sender: [email protected]
    MIME-Version: 1.0
    Content-Type: multipart/alternative;
      boundary="=_b308d10660951d296cc57d268c770c5f"
    Sender: Stephen Switzer <[email protected]>
    Date: Mon, 19 Dec 2016 23:55:55 -0500
    From: "RT, Support" <[email protected]>
    To: [email protected]
    Subject: Re: [SBS #99845] Laptop will not connect to the internet
    In-Reply-To: <[email protected]>
    References: <[email protected]>
      <CY4PR10MB16247C062AD6E90C674E7AE1B4900@CY4PR10MB1624.namprd10.prod.outlook.com>
      <[email protected]>
    Message-ID: <[email protected]>
    X-Sender: [email protected]

Yes, I sanitized, even though you can deduce what it really was easily... :)

I grep'd the RT code, and found that lib/RT/Interface/Email.pm seems to 
be what is responsible... but no obvious line that tells me this code is 
used for OUTBOUND email. Can anyone shed some light on this issue? I'd 
be happy to hack code, I just want it fixed.

Thank you!

-- 

Best regards,
Steve

		
Stephen H. Switzer
President & Chief Technical Consultant
	
[email protected] <mailto:[email protected]>
	
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