Recently the frequent spammer Thierno Sow has returned to MSE. My question isn't directly related to their return, however - rather, I want to ask about a curiosity around the comment system.

I wrote a comment to one of these questions; this comment read roughly "I do not recommend engaging Thierno Sow." When I tried to submit it, I got an interesting error message:

"Comments cannot contain this content."

Experimenting, I found that any comment containing "Thierno Sow" is blocked (although "Thierno M Sow" is not blocked). Another user has commented that their name is also prevented from appearing in flag text. And, when I tried to ask a test question, I got the more specific error message

Body cannot contain "Thierno Sow".

(Interestingly, their name is not blocked from questions on the meta site.)

I'm a little disturbed by this, to be honest. While of course the person in question has nothing to contribute to this site, I am not entirely comfortable with comments being censored in this (to be fair, extremely mild and easily circumventable) way. So I want to ask two questions:

  • How did this happen? In particular, what is the policy for determining that a given phrase is no longer allowed to appear in comments?

  • Is this something that the community is comfortable with? I'm willing to put aside my concerns if this is generally accepted, I suppose, but I was completely unaware of it until now, so I would love a reality check.

  • 1
    $\begingroup$ I'm not that familiar with how the site moderates comments, but is there a similar system for profanity? i.e. do you get a similar error message if you attempt to post a comment (or question on the main site) with profanity? $\endgroup$
    – mrnovice
    Apr 13, 2017 at 16:09
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    $\begingroup$ @mrnovice Definitely not - I've seen comments and questions with plenty of profanity. When I tried to post a test question with the name of the spammer in it, as soon as I tried to enter a tag I got an error message; but I just wrote a post with several swear words in it, and got to the point where I could submit it without issue (I didn't feel comfortable actually submitting it though, even though I would delete it immediately after). And I did just add (and then immediately delete) a comment with plenty of profanity, without issue. The relevant name seems unique in this respect . . . $\endgroup$ Apr 13, 2017 at 16:10
  • $\begingroup$ Then this does seem very strange, hopefully this question attracts the attention of a moderator who could shed some light on why this is the case. $\endgroup$
    – mrnovice
    Apr 13, 2017 at 16:12
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    $\begingroup$ On one level, I can shed light: there's an entry - apparently fairly new - in the list of blacklisted user input (on the main site). I don't know who added that entry, when, and why, though. Trying to find out. $\endgroup$ Apr 13, 2017 at 16:14
  • $\begingroup$ This sounds like a custom blacklisted phrase, which as far as I'm aware get added by the SE team and affect all user-generated content input, including comments. $\endgroup$
    – ArtOfCode
    Apr 13, 2017 at 16:24
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    $\begingroup$ @mrnovice there are certain words whose addition to a comment allows deletion by a single rude/offensive flag, but they're not many. Second ArtOfCode, I think this is a custom blacklist, and really, you should ask it to be harder to circumvent. $\endgroup$
    – M.A.R.
    Apr 13, 2017 at 16:46
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    $\begingroup$ A comment at the linked post adds: “It seems that his name can not even be mentioned in flags to mederators! (My flag didn't get sent because it contained "blocked text" or something like that.)” $\endgroup$
    – MJD
    Apr 13, 2017 at 17:44
  • $\begingroup$ Who is Thierno Sow ? I can't see deleted questions. $\endgroup$
    – user312097
    Apr 13, 2017 at 19:17
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    $\begingroup$ @A---B randomprocessed.blogspot.fr/2014/01/… $\endgroup$
    – Did
    Apr 13, 2017 at 19:53
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    $\begingroup$ Strangely, the old account is still there. $\endgroup$ Apr 14, 2017 at 19:28
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    $\begingroup$ @Did: Your link does show the stature of this person and I am glad that good sense prevailed here to block such content. This reminds me of Richard Dawkins saying "By all means let's be open-minded, but not so open-minded that our brains drop out." $\endgroup$
    – Paramanand Singh Mod
    Apr 16, 2017 at 4:11
  • $\begingroup$ @ParamanandSingh Nice quote. $\endgroup$
    – Did
    Apr 16, 2017 at 7:52
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    $\begingroup$ The Chinese have more experience with making good software to deal these sorts of problems. $\endgroup$ Apr 16, 2017 at 18:57
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    $\begingroup$ Indeed, it was me trying to flag one of those posts to a moderator's attention, but having to give up because my flag contained unacceptable terms (which, I believe, was the name of T.M.S.). $\endgroup$
    – Alex M.
    Apr 20, 2017 at 17:41

1 Answer 1


Yes, this is universal blacklist. Both MathOverflow and this site have had problems with this particular person. MathOverflow moderators have, at times, asked to have content blocked preemptively. (I'm not going to be too specific here to avoid making the blocks easier to avoid.) When I add a blacklist item over there, I tend to add it here as well. (Looking back on my notes, I don't see that a Mathematics Stack Exchange moderator has asked for this, but I seem to recall someone had. I might be mistaken.)

Generally, blacklists are not a great idea as they have a tendency to block too much if too broad and be easily worked around (V!agra) if too narrow. We tend to implement them only when we can be pretty certain we are blocking the problematic string. For instance, we can safely block lmgtfy.com everywhere since there's no non-sarcastic reason to use that link. The blocks you are asking about are along the same lines. (In fact, those are the only two things we currently block everywhere on this site.)

A few notes that might help make the situation less, um, ominous:

  1. Only the community managers add blocks and we are reluctant to use them in most cases.

  2. Blocks are occasionally audited automatically. I won't go into the details of the process, but just because a string is blocked today does not mean it'll be blocked forever.

  3. As you noticed, we don't block the same strings on Meta as we do on the main site. This is so you can talk about inappropriate blocks, if needed.

  4. I'm happy to remove this particular block from this site if y'all would rather delete posts than prevent them.

  • 5
    $\begingroup$ I guess my response to this is focused on 4: I don't think this does prevent such posts. There are plenty of ways around it - plenty of ways to even produce the forbidden string - and besides, the person in question can just ask their question without mentioning their own name. Is there any evidence that this actually prevents (or decreases the frequency of) anything? Two posts within a couple days of each other matches this spammer's general pattern, if I recall correctly . . . $\endgroup$ Apr 13, 2017 at 18:27
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    $\begingroup$ That said, +1 for information. $\endgroup$ Apr 13, 2017 at 18:28
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    $\begingroup$ @NoahSchweber: So this user seems particularly interested in self-promotion. The name block does seem effective, but gets removed on occasion because of #2. There have been other blocks that have been less effective. Personally, I think the blacklist is more trouble than it's worth. But I'm not the one who has to delete the posts and user accounts. $\endgroup$ Apr 13, 2017 at 18:53
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    $\begingroup$ Thanks. Let's see if the block works as intended. I may have asked for a block on this person's IP when destroying one of the clones. May be you recalled that? Anyway, the tools diamond moderators have access to are mostly sufficient for handling this case. The spammer is not spawning dozens of accounts weekly - the attempts to claim the soap box are thankfully much rarer. $\endgroup$ Apr 13, 2017 at 19:48
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    $\begingroup$ Blocking terms on the main site is fine with me, but why also do it in flags to the moderators? If you chose not to block them on Meta (which makes sense, as you explain), why block them in flags then? $\endgroup$
    – Alex M.
    Apr 20, 2017 at 17:43
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    $\begingroup$ Jon, unfortunately they seem to have figured this out. $\endgroup$ Apr 22, 2017 at 8:16
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    $\begingroup$ Can you block one-zero.eu as well? In the last series of posts (e.g. this one), the person puts a link to this website in the first comment, which avoids detection by SmokeDetector. $\endgroup$
    – Glorfindel
    Apr 24, 2017 at 8:25
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    $\begingroup$ @JyrkiLahtonen: Is there a bug or something? That linked post says "show 1 more comment" but clicking on it produces nothing. $\endgroup$
    – user21820
    Aug 8, 2021 at 2:07
  • $\begingroup$ @user21820 I don't know what's going on there. A bit strange. $\endgroup$ Aug 8, 2021 at 4:03

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