How to protect a Telegram group from spam
Entry checks, flood control, a newcomer sandbox and word filters — what each one actually stops, and why an unexplained ban costs you more than the spam did.
Spam in a Telegram group arrives in three shapes, and each needs a different answer. Confusing them is why so many groups end up either overrun or over-moderated.
Shape one: bots at the door
These accounts join and post within seconds, often the same message across hundreds of groups. Content filters catch them late — after the message is already visible.
The cheap answer is an entry check: a button or a small maths problem before the first message. A bot either fails it or does not bother. A person spends two seconds.
Shape two: humans selling something
They join, wait, then post an advert that no keyword list predicted.
Filters help, but only if they survive the tricks: казиноо with a
doubled letter, kаzino where one letter is Latin, or zero-width
characters glued between letters.
A filter that folds lookalike letters back and matches word endings catches all three. A naive one catches none.
Shape three: flooding
Sometimes nothing in the text is forbidden — there is simply too much of it, too fast. Frequency limits handle what content filters cannot: N messages in M seconds, then a temporary mute rather than a ban.
The newcomer sandbox
Most damage comes in the first hours after joining. A sandbox that forbids links, media and forwards for the first day removes that window without touching regulars. It is the single cheapest rule you can turn on.
Why the log matters more than the ban
Every automated decision is a guess. Sooner or later it hits a real person — and then the question is not whether it happened, but how fast you can see it and undo it.
That is why a moderation log should say three things: what was deleted, why, and by which rule. With those, an owner fixes a wrong decision in one tap and teaches the filter at the same time. Without them, members just see messages disappearing and quietly leave.
A sane default
Start with log only: the bot watches and writes down what it would have done, but deletes nothing. Look at the log after a week — you will know exactly which rules to turn on, and you will not have banned anyone by accident while learning.