A peek into Reddit's anti-spam internals

https://lyra.horse/blog/2026/06/reddit-spam-internals/

by OuterVale • 25 days ago

185 77 25 days ago

ingvay7• 25 days ago

Neat rabbit hole. Reminds me of having to deal with email spam - it was a similar deal with rule-based filters, ML scores, domain bans,IP filtering, browse fingerprinting etc and mishmash of ever evolving scripts surviving org and personnel changes. Glad i dont deal with it anymore as the frontier seems to be 2 fronts now with human and agentic spam.

Terr_2• 25 days ago

Damn, maybe I can finally find out why my 10+ year account was globally (and retroactively) shadowbanned, even though the appeal was allegedly granted.

In the past, those post removals didn't even exist in the moderation log, so perhaps a reason could give me a clue... On the other hand, I'm taking a kind of emotional damage just remembering.

qingcharles3• 22 days ago

Is it still shadowbanned? If you go to reddit.com/appeal what does it say?

someonebaggy6• 22 days ago

There's basically only one result you can get from an appeal which is "we have reviewed your account and we will not be lifting the suspension at this time."

The appeals process exists to fill a checkbox that says there must be an appeals process, not to actually unban anyone.

Terr_2• 18 days ago

As I said, the appeal was granted, or at least that's the message I got in reply.

However everything remained in the nether-realm and the appeals page claimed that my account was normal, and that therefore couldn't be used

No response from any support ticket either. They still advertised me IPO opportunities though...

randysalami3• 25 days ago

Reddit must have some mechanism specifically for non-spamming bots that isn’t covered in this article. I wonder how it works. I imagine the mechanisms are more complex and opaque than anti-spam (with various levels being exposed to the hierarchies of Reddit and government backdoors). These days, I’ve noticed an almost forcing-function that operates to put the minimum spin needed on posts and comments to turn signal to noise. It seems smart enough to not only generate noisy comments but create comments to amplify existing organic noisy comments. I’m sure these systems are decentralized, emergent, and split across numerous nation-states and actors. I’m also fairly certain what we have now is a tenuous balance that has emerged from all these actors and Reddit policing actions as well.

I imagine Reddit has a high-level of insight into this and a certain level of permissibility it grants, both to inflate user counts and to steer public discourse and insight into less productive mean (or productive to certain interest groups at the expense of the people). I think is also an effect that Reddit has become more global and consensus of the USA people is very antagonistic to the consensus of the people of the world so that doesn’t help (+ access to LLMs to make English writing no longer a barrier to entry).

asdff2• 22 days ago

There is some sort of wink wink nudge nudge agreement going on with certain spam accounts. You will see them post article spam with hidden history, and if you look up their posts either via google or any other reddit crawling tool, they are posting all over various subreddits that same article maybe dozens of times. If they comment it is really basic and formulaic and found all over their post histories as well.

I feel like reddit enjoys it as these posts (often political in some way) usually get good engagement which is in line with reddits own incentives for courting advertiser money.

hightrix• 22 days ago

This practice was perfected by gallowboob years ago.

He would spam a link/pic/post and monitor, if the post didn’t gain traction, he would delete and post again as to not trigger protections against the same link being posted.

He was a cancer on Reddit and I’m sure he still exists under different monikers. But now there are 100s of gallowboobs.

someonebaggy6• 22 days ago

There have been incidents where users who reported certain spambots were themselves banned for "report abuse". It's speculated the operators of those spambots pay money to Reddit to not be banned.

busymom0• 22 days ago

I swear I read this article 2 or 3 days ago and the comments on that post were also same as this post. Am I missing something here?

yorwba• 22 days ago

You're missing the second-chance pool https://news.ycombinator.com/pool which allows certain posts to reappear as if they were new.

asdff2• 22 days ago

Once again expressing my opinion that this is the worst anti feature of the site. Threads are like commenting in the void because most people are not going to be looking for replies to comments they made days or weeks ago. I see the true datestamp of the comment I replied upon upthread was not 3 hours ago, but 3 days ago.

The fact that they change the timestamp is also very stupid (yes you can hover and still return the datestamp, but this is by definition a dark pattern). These posts should preserve the timestamp vs masking it and even should be flagged as [Second Chance] in the title imo.

khurs• 22 days ago

That doesn't show for me unless I click the link.

How does it work?

rebane20012• 22 days ago

wait what the heck yeah, this is the same post as from a few days ago, i guess the comment and post timestamps got glitched??

nancyminusone• 22 days ago

That'a thing HN's second chance pool does. If you mouseover the "3 hours ago" or whatever on a comment, it will tell you the actual post timestamp.

qingcharles3• 22 days ago

There have been almost zero visible changes to the HN codebase in over a decade, but the one thing I would love to see them add is a little flag on the heading of the post to say it is 2nd Chance Pool to avoid all these comments every time this happens and everyone is confused :)

felooboolooomba2• 22 days ago

My friend got shadowbanned for posting a youtube link, part of a interview with Sascha Riley (the one where the explains the thing with the tent peg):

https://www.youtube.com/watch?v=84PHEMLab6g&t=2807s

someonebaggy6• 22 days ago

You get shadowbanned for almost anything these days. It's not worth trying to use that site any more - I wrote it off as a lost cause, a playground for bots to talk to each other thinking they're talking to humans.

felooboolooomba2• 22 days ago

The Russian bots on there trying to demoralize the UK are pretty hilarious too.

Oarch• 22 days ago

Can't you just append ".json" to the end of any Reddit link and read all sorts of these fields?

rebane20012• 22 days ago

No, the API will not return the admin-only removal reason. The code path that causes this is in the post.

leviathant3• 22 days ago

I cannot emphasize strongly enough just how deeply pervasive the spam is at Reddit. I'm a mod at the ecommerce subreddit, and I've only caught some of the AI-powered marketing operations because in one particular campaign that was making fictional claims about things I had direct knowledge about. Once I looked into the post history, and started to untangle the web of accounts that formed a self-supporting community of posters and commenters, just subtle enough to get genuine engagement, but specific enough to make the kind of posts that the LLMs will siphon up and regurgitate.

It's not just shady little operations. I'm speaking specifically about the SCAYLE ecommerce platform, in my example. They've got Zalando money to play with, and as a German platform that's trying to break into the North American market, it appears they've made a bet on indirectly spamming the LLMs with fictional tales of commerce replatforming horror stories. At first, they're some of the more interesting topics in a sea of really useless posts, with contributions from people who seem to have some real experience with enterprise ecommerce. I was a little suspicious, but these interaction campaigns were spread out enough that I didn't put the pieces together for months. Of course, to go back on what I said at the top of the paragraph, maybe SCAYLE is shady, and I'm giving them too much credit.

The good news is, some of the AI powered tools that mods have access to are getting better at surfacing suspicious patterns of behavior. However, I still find I have to manually address these campaigns.

In the cat-and-mouse game with these marketing jerks, I'm always reluctant to surface what's working and what isn't. This is an interesting post, but it's going to make things worse. Ah well.

jamesfinlayson• 22 days ago

I remember reading years ago about some corrupt mod in one of the image subreddits - he or his friend had started some image hosting site and had six different Reddit accounts that he used to upvote posts that used his site and downvote all other posts. It took people a long while to notice what he was up to.

leviathant3• 21 days ago

And now automate and scale that with Claude/OpenAI/Gemini/whatever. It's insidious and terrible.

justcool3935• 19 days ago

the Unidan incident?

iirc it only got noticed at the time because of an argument between him and Ecka6 which led to the somewhat famous "here's the thing you said a jackdaw is a crow" copypasta

someonebaggy6• 22 days ago

The flip side of this is that for many years it's been basically impossible for a real person to convince Reddit to let them have an account. They track so many signals and if they don't like a single one or a combination, you get shadowbanned - I've tried it a few times since then on different computers on different networks with different email addresses, and I concluded they must have an extremely specific idea of what a new user does and everything else is spamming. For example if I post a few comments within a few hours of signing up, I was always shadowbanned. Because that's what a new user does, you see.

I stopped trying to have a Reddit account in about 2024 when the platform was too obviously enshittified, with no content of any value whatsoever remaining on it.

EA-3167• 19 days ago

Once Discord started taking off I was much happier returning to the chatrooms I started with (on IRC), without any algorithm attempting to maximize your engagement. It's much less useful as a resource that grows over time, but the value of something like that has been slashed and burned by LLM's anyway.

In the end the biggest hurdle to getting an account on Reddit at this point is why you'd bother.

TFNA• 19 days ago

For the last several years, I’ve created a new Reddit account, posted heavily, and then deleted it when I felt I needed a social-media break. Rinse and repeat. I’ve never had problems creating those new accounts or having them banned. You just need to verify your signup with some new email address, at some domain that isn’t already a known throwaway-email domain, and accept that some subs won’t show your comments until your account is a couple of weeks old.

But I definitely agree with you that the platform is finished now, even smaller subs that aren’t drawing so much surreptitious spam. The problem is that even if one uses Old Reddit, the vast majority of other posters are using the app. That tends to discourage substantial discussion or community, in favour of daft 140-character shit comments.

lelandfe2• 21 days ago

I'm sure you love Reddit's decision to allow users to hide their post history.

leviathant3• 21 days ago

What I do love is that when you're a mod, that post history isn't necessarily hidden.

Cider99862• 19 days ago

I hate that change. arctic-shift.photon-reddit.com still works, at least with comments before the change. Not sure about current comments.

ThatMedicIsASpy• 18 days ago

The same as youtubes removal of dislikes and more recently they disabled search results with newest results first.

Now I ignore a user based on other criteria (account age post/comment karma + a 50 times compressed repost)

kps2• 18 days ago

They still let Google crawl, so [site:reddit.com "username"] can be instructive.

hn8726• 19 days ago

I'd be surprised if Reddit wasn't selling tools specifically aimed at seting up and managing operations like that

ACCount37• 19 days ago

I would be surprised if Reddit was selling tools like that directly. Rather than just look the other way - because uncovering modern bot operations is a thankless threadmill, and user engagement metrics from fake users are still user engagement metrics.

VierScar3• 19 days ago

How did you manage to uncover the operation? Is there any things that tipped you off? Is it like, accounts only posting on a precise subset of subs, or how much a network of accounts reply to each other? Or too much linking/references to products, or perfect spelling/identical consistent typos?

I'm curious because it feels like it could be built into a tool to analyse - even if it does become a bit of an arms race.

Rebelgecko2• 19 days ago

It's harder now that post history is hidden but I did something similar in the past.

Start with a single comment you think is a shill. Maybe 80% of their post history is vague inane generalities (like "aww so cute" in r/cats, or a reply to a top rated post that only paraphrases the existing context without adding anything new). You can use an LLM to identify every comment or post from that account that mentions a product or service. Take note of everyone who replies to that comment as well as the parent comment. Then use an LLM to identify every post from that original account asking for recommendations (hey r/bidet, what's your favorite bidet), and look at who responds. If you build this graph, draw directional edges based on who replied to who. The accounts with edges both ways across different posts are bots. Rinse and repeat by examing the post history of THOSE accounts. You will end up with a graph with a few loosely connected nodes (maybe false positives) but a tight web of spam accounts that frequently engage with each other.

That's your bot farm. This would be relatively trivial for reddit to implement, if they cared about reducing spam. I got a POC working in a few hours, back before they limited API access

speckx• 18 days ago

I can't even fathom how mods now handle all this. I was a mod for one of the top subreddits and it was hard back then, a few years before LLMs, and I only had to deal with URL submissions, not comments.

I also help moderate a forum and I noticed the spike in new user signups for spamming has sharply risen over the last two years or so. The majority are most likely using LLMs to automate this. So now we put new registered users into a shadow account where they can post and interact, but it's only visible to them and no one else on the forum for a probation period. It seems to work for now.

pedalpete• 22 days ago

Based on the current status of my shadowbanned account (I suspect a competitor in our space retaliating), it looks like `banall` only flags posts from the last 6 years.

Of course, nobody can view my profile anymore anyway (I'm waiting on appeal), but on my account, only posts from the last 6 years have the "Sorry this post was removed by reddit filters" message.

try-working2• 19 days ago

what's going on with this post? It was posted days ago and now its back on the frontpage again?

aw1621107• 19 days ago

My guess would be the second-chance pool (https://news.ycombinator.com/pool, explained by dang at https://news.ycombinator.com/item?id=26998308)

gnabgib• 19 days ago

Exactly that, you can tell by hovering over the posted time "9 hours ago".. and see that it's really from June.

kaszanka• 19 days ago

"Anti-Evil Operations" is a pretty grandiose name for spam filtering. Also I liked the House of Leaves reference

justcool3935• 19 days ago

ya it really is. it's the new name (where new is relative to like 10 years) for Trust & Safety.

ecshafer• 19 days ago

"Anti-Evil Operations" is the name of their wrong think filtering, which is hilarious in a newspeak kind of way.

PUSH_AX• 19 days ago

A lot of what they are doing now is around AI comments and posts, I know this because in some of my subreddits I have various automod filters that align with the way AI writes, I see it all the time where my automod removes something and reddit removes it again after (some kind of race condition), as well as tons of these accounts getting site wide bans.

In case you didn't realise, a massive portion of content on reddit now is LLMs.

I'm not a massive fan of how reddit has played certain hands in the last 5 years or so, but I do hope they win the war on dead internet theory.

Scoundreller• 19 days ago

I suspect their IPO is a sign that they’re throwing in the towel existentially.

justcool3935• 19 days ago

some more information perhaps?

banned_by true is more accurate to say "admin or automatic". in "admin mode," you can see these although not sure the UX for these nowadays now that it is spewing a gazillion lines of text into them).

Anti-Evil Operations removals (nee Trust & Safety) are generally human(-assisted) actions (although these actions can be applied en masse). there's some more information nowadays in the API which was really nice. it also helped because people stopped blaming "the mods" for removals when the spam filter slopped all over the place. this was also annoying because previously you had to previously guess from the API how it was removed even if you were a mod.

the 3 ways to remove a post/comment (i.e. in reply to: train_spam):

- remove not spam: removes it but doesn't train the spam filter, obvious

- spam: removes it and trains the spam filter, obvious

- confirm spam: only happens when you remove after removing for any reason, *does not* train the spam filter

- reinforce spam: trains the spam filter even if the spam filter already caught it. *does* train the spam filter. you can do this by doing `action: spam` in automod. not sure if there have been any more in the last few years

also you can tell the legacy of "removals", back in the day stories were "banned" instead of "removed" by moderators and administrators.

also also also... you can see a lot of the stuff from this article in the `approved_by` side of it as well. if you hover over a checkmark of someone who has been unshadowbanned, you'll see it says "approved by Reddit (shadowban removed)"

if an admin manually unspams someones stuff (say someone who got accidentally shadowbanned and got hit with an overzealous spam filter multiple times >.>), it'll say "approved by <username> (all)". there are some consequences to this. it approves stuff that has been "filtered" (as AutoMod filtering is a weird hack where it removes something but keeps in the modqueue).

spammit

i believe this is the thing that is "pretty similar to a naive Bayesian classifier"[1][2] that reddit used. /u/Deimorz iirc was a reddit dev at the time and it was somewhat public info. i say somewhat because you kinda had to be both interested in the this and probably be around the metasphere

iirc from some other comments i pieced together there are also per-subreddit spam filters. in the olden days sometimes they'd get way out of whack and you could ask an admin to reset it for you... or something idk

em

guessing em in this case btw refers to /u/hueypriest, who was reddit's GM at the time

would’ve been catastrophic for Reddit’s spam issues

the thing that surprised me at the time was just how bad reddit's spam filtering is. i did a small little thing at the time where i'd just look at stuff following some basic spam filtering rules (like stuff you'd probably get out of an artisinal spamassassin ruleset) and even that deluge was amazing to see.

like the ML stuff is cool and all but seriously 90% of this could probably still be solved with some basic rules. the profile hiding stuff didn't help either but that was way after my time.

[1] https://reddit.com/r/TheoryOfReddit/comments/10ko5h/comment/... (2012)

[2] https://www.reddit.com/r/modnews/comments/6bj5de/state_of_sp...

forestry• 19 days ago

My takeaway:

My test account (5 years old!) got banned immediately, and all of its post history got wiped too. RIP

I want to know the real string of the event I ever want to delete my account and content. This would be much faster than using a browser script to manually delete.

A peek into Reddit's anti-spam internals

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