Source: https://tgdog.wadesk.io/guide/spam-filter-rules/

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# Keyword, repeated-message and anti-flood rules

Tune your Telegram spam filter with matching limits, thresholds and evidence.

[TGDogProduct documentation](https://tgdog.wadesk.io/about/)Published Oct 9, 2026 Updated Oct 9, 2026 2 min read

AT A GLANCE
- Start with narrow terms and Observe mode.

- Similarity scores are not spam probabilities.

- Review repeated-message and anti-flood settings separately.

## [Match the language that matters.](https://tgdog.wadesk.io/guide/spam-filter-rules/#match-the-language-that-matters)

Enter one keyword per line, up to 30 terms with at most 80 characters each. A contained keyword can save matching evidence from a single message. Optional fuzzy matching detects text variations with a configurable similarity threshold from 0.70 to 0.98; the default is 0.85.

## [Fuzzy matching limits](https://tgdog.wadesk.io/guide/spam-filter-rules/#fuzzy-matching-limits)

Terms shorter than four characters use containment matching only. Fuzzy checks are limited to the first 500 characters of each message and a per-group computational budget. Similarity is not a spam probability, and limited budgets may miss matches.

## [A containment match example](https://tgdog.wadesk.io/guide/spam-filter-rules/#a-containment-match-example)

Keyword: `free giveaway`

Message: “Join our free giveaway today.”

Evidence saved in Observe mode

## [Repetition, near duplicates and anti-flood](https://tgdog.wadesk.io/guide/spam-filter-rules/#repetition-near-duplicates-and-anti-flood)

Repeated messages, near duplicates, and short bursts of posting have separate detection settings. Enabled detection kinds can use the group’s chosen Observe, Block or Remove action; leave Observe selected if you only want evidence.

## [Recommended presets by community type](https://tgdog.wadesk.io/guide/spam-filter-rules/#recommended-presets-by-community-type)

- Web3 & Crypto groups: Target phishing phrases (`airdrop`, `claim reward`, `seed phrase`, `presale`), enable near-duplicate checks, and set strict flood limits (e.g. 3 messages within 5s). Start in Observe mode, then switch to Block for confirmed malicious links.

- Developer communities: Use targeted marketing phrases; keep repetition thresholds relaxed (5+ occurrences) to avoid flagging shared code snippets or error logs; maintain whitelists for maintainers.

- Local & Hobby groups: Add recurring ad expressions; enable 60-second repeated-message detection; use Observe mode to test rules before switching to Remove for persistent ad accounts.

## [Check your setup](https://tgdog.wadesk.io/guide/spam-filter-rules/#check-your-setup)

- Start with narrow terms and Observe mode.

- Similarity scores are not spam probabilities.

- Review repeated-message and anti-flood settings separately.

## [Where to go next](https://tgdog.wadesk.io/guide/spam-filter-rules/#where-to-go-next)

If you are setting up TGDog for the first time, follow the [complete How to use tutorial](https://tgdog.wadesk.io/how-to-use/). For a deeper explanation of another topic, return to the [Guide library](https://tgdog.wadesk.io/guide/).

TGDogTGDog product documentation. Written from the extension implementation and checked against official Telegram references.

[About the author](https://tgdog.wadesk.io/about/)

[← Previous articleSupergroups, admin permissions and whitelists](https://tgdog.wadesk.io/guide/group-rules/)[Next article →Observe, Block and Remove: what each action does](https://tgdog.wadesk.io/guide/member-actions/)