It was thus said that the Great Chuck Guzis via cctalk once stated:
  On 02/28/2017 03:40 PM, Paul Berger wrote:
  Well I am using Thunderbird 45.7.1 and I see this
"Chuck Guzis via
 cctalk <cctalk at classiccmp.org>" as "From" in your message.
  
 Hmmm, this is very puzzling.  Your message does indeed show up as being
 from "Paul Berger", by the message you replied to shows up as being from
 "CCtalk"
 Is someone tweaking the system as we speak? 
  Here are the critical headers from your (Chunk) email:
        List-Post: <mailto:cctalk at classiccmp.org>
        From: Chuck Guzis via cctalk <cctalk at classiccmp.org>
        Reply-To: Chuck Guzis <cclist at ----.com>,
         "General Discussion: On-Topic and Off-Topic Posts"
         <cctalk at classiccmp.org>
        Errors-To: cctalk-bounces at 
classiccmp.org
        Sender: "cctalk" <cctalk-bounces at classiccmp.org>
  The from address is cctalk at 
classiccomp.org.  The reply-to addresses
contains your (Chuck) email address (blanked out) in addition to the cctalk
address.  An email will use the reply-to address, but I could see an email
client using the list-post address when replying (since that informs the
email client that this email from a mailing list).
  So here we have From: munging (that's a twist!) and Reply-To: munging but
by adding an address instead of outright replacement (intresting solution to
munging [1][2]).  So when you (not Chuck) hit reply, it goes to your (Chuck)
email address and cctalk.
  -spc (Who runs his own email server ... )
[1]     "Reply-To" Munging Considered Harmful
        
http://www.unicom.com/pw/reply-to-harmful.html
[2]     Reply-To Munging Considered Useful
        
http://marc.merlins.org/netrants/reply-to-useful.html