How to cut most of automated spam in Telegram channel comments

Of the many problems that Telegram has, the one which frustrates me the most is a ton of automated spam — as it has absolutely no automated antispam measures.

It annoys me especially in the “comment chats”. They are linked to public channels and auto-discoverable by spam bots. With a bit of tinkering, anyone on the internet can send any text to a chat with a known number of recipients and a known topic.

Sometimes I wake up to clean 20+ spam messages for multiple days in a row.

The only fix that is available via the built-in Telegram features is to set the comment chat to manual approval of new chat members.

But due to the nature of Telegram comments, which are basically a regular chat taped to a channel (olympiadniki, blyat), this approach has serious downsides:

1. You need to approve them manually. A person who wanted to write a comment will lose interest if you are late with the approval, ruining the quality of the discussion
2. People who commented on the post will now get a notification for every comment under every post. That’s why most users will want to leave after writing a comment
3. Once they leave, they need to go through step 1 again

How can we automate approvals without auto-approving spammers?

I discovered that these automated spammers don’t bother joining the channel — they go to the comments directly, as it seems to be exposed in the API.

So when your comments chat receives a join request, it must be matched against a subscriber of the channel.

You still need to auto-approve real people who visited your channel without joining it. But these are rare, and usually they leave low-value negative comments that can wait :)

Doorman bot

It was very trivial to build a bot that does that. My bot is called @doorman_da_bot

As the bot doesn’t require any configs and isn’t resource-heavy — you can use it for free.

You need to add the bot as an admin to both the channel and the comments chat with a minimal set of rights. You only need to give the “Add members” right in the comments chat and the “Add subscribers” right in the channel.

There is no reason to give it any other rights.

If you are worried about security — you can give this post to an LLM and have it one-shot this bot for you.