What is true is that the troll's message will not appear in the list's archive. (That's how I became aware that one person was actually a troll; I went to the archive, and, huh? This guy is not there! And neither are my replies to that guy. What the .... Then it immediately dawned on me!)

But, yes, trolls will be replied to. Because, remember, they are not even going through the mailing list robot. They are just sending mail. Of course the troll's mails can be replied to and go back to that person, and to everyone on the CC list that he or she put in.

Not only that, but the troll can include the list address on the CC: line! A reply to the troll will include quoted material from the troll (typically), and since the person responding is a valid subscriber who is allowed to post, that quoted material gets to the list.

So all the list subscribers end up seeing:

  On Monday, October 6, 2014 T. Roll wrote:
  > Inflammatory crap  ...

  I disagree with your inflammatory crap!

Nobody on the has the original message with the full inflammatory crap (except those on the CC: list of that troll thread including the person writing the above response). But thanks to this reply and others like it, everyone on the list continues to have glimpses into what T. Roll thinks. (They are is even trimmed nicely to give the list members just the most inflammatory parts!)

But if the list is set up differently you can get it so people don't use reply all by default, and even better they can tell at a glance if a mail came from the list or not.

Does anybody remember the nettime mailing list, and the amazing ascii graphics code-poetry performance art trolling (and excellent personalized customer support) by Netochka Nezvanova aka NN aka antiorp aka integer aka =cw4t7abs aka m2zk!n3nkunzt aka punktprotokol aka 0f0003, the brilliant yet sociopathic developer of nato.0+55+3d for Max? Now THAT was some spectacular trolling (and spectacular software).

https://en.wikipedia.org/wiki/Netochka_Nezvanova_(author)

https://en.wikipedia.org/wiki/Nato.0%2B55%2B3d

http://jodi.org/

http://www.salon.com/2002/03/01/netochka/ The name Netochka Nezvanova is a pseudonym borrowed from the main character of Fyodor Dostoevski’s first novel; it translates loosely as “nameless nobody.” Her fans, her critics, her customers and her victims alike refer to her as a “being” or an “entity.” The rumors and speculation about her range all over the map. Is she one person with multiple identities? A female New Zealander artist, a male Icelander musician or an Eastern European collective conspiracy? The mystery only propagates her legend.

Cramer, Florian. (2005) "Software dystopia: Netochka Nezvanova - Code as cult" in Words Made Flesh: Code, Culture, Imagination, Chapter 4, Automatisms and Their Constraints. Rotterdam: Piet Zwart Institute. https://web.archive.org/web/20070215185215/http://pzwart.wdk...

    Empire = body.
    hensz nn - simply.SUPERIOR
    
    per chansz auss! ‘reazon‘ nn = regardz geert lovink + h!z !lk
    az ultra outdatd + p!t!fl pre.90.z ueztern kap!tal!zt buffoonz
    
    ent!tl!ng u korporat fasc!ztz = haz b!n 01 error ov zortz on m! part.
    [ma!z ! = z!mpl! ador faz!on]
    geert lovink + ekxtra 1 d!menz!onl kr!!!!ketz [e.g. dze ultra unevntfl \
    borrrrrrr!ng andreas broeckmann. alex galloway etc]
    = do not dze konzt!tuz!on pozez 2 komput dze teor!e much
    elsz akt!vat 01 lf+ !nundaz!e.
    
    jetzt ! = return 2 z!p!ng tea + !zolat!ng m! celllz 4rom ur funerl.
    
    vr!!endl!.nn
    
    ventuze.nn
    
       /_/  
                             /  
                \            \/       i should like to be a human plant  
               \/       _{  
                       _{/  
                                      i will shed leaves in the shade  
           \_\                        because i like stepping on bugs