Email Bot Detector: Know When a Bot Is in Your Inbox

Not every automated email is the same — and treating them the same way leads to missed connections or missed threats. AgentProof gives you precise classification: autonomous AI agent, human-driven sequence, transactional automation, or real human. One badge. No guessing.

Types of email bots

The word "bot" gets used loosely. In the context of email, there are meaningful distinctions:

• Autonomous AI agents (agents) — LLM-powered systems that research, personalize, and send email without per-send human involvement. Examples: 11x, Artisan, custom LangChain pipelines. These are the hardest to detect and the fastest-growing category.
• Sequenced outreach bots (sequences) — a human wrote the templates and set the trigger rules; software sends them. Examples: Apollo sequences, HubSpot Sequences, Outreach.io. A human decided to send it; a machine sent it.
• Transactional bots (auto) — company-to-user automated email: receipts, account alerts, shipping notifications, newsletters. These are expected and wanted — not a threat.

Most "email bot detector" tools lump all three into "spam." AgentProof classifies all three separately so you can make the right decision for each one.

How bot email detection works

Email bots leave signals at every layer of the email: the transport headers, the MIME structure, the sending infrastructure, the timing of delivery, and the text itself. AgentProof checks all of them:

• Transport layer: X-Mailer, X-Mailer-Version, DKIM signing domain, Message-ID format, received-chain hop count
• Infrastructure: sending IP range against known ESP blocks, SMTP server hostname patterns, SPF alignment
• Timing: send time relative to prior messages in thread, inter-message interval variance, timezone consistency
• Content: sentence length variance, lexical diversity score, personalization ratio, structural template matching, AI opener formula detection

False positive protection

The biggest failure mode of any detection tool is flagging real humans. AgentProof uses five whitelist protections that always reduce the score:

• Sender is in your Google Contacts (score × 0.3)
• Prior conversation exists in thread history (score × 0.5)
• Calendar correlation — you have a meeting with this person (score × 0.4, Pro)
• Reply-chain human markers: typos, "Sent from iPhone", casual punctuation (score × 0.6)
• User-confirmed human: you've manually marked this sender as human (score = 0)

On labeled test data: 88% recall on agent emails, 0% false positive rate on real human emails. Medium-FP signals never cause a flag alone — they only boost a score already elevated by corroborating low-FP signals.

Installing the email bot detector

AgentProof is a free Chrome extension that installs in 30 seconds. Once installed, it automatically starts scoring every email in your Gmail inbox — no configuration, no rules to write, no email forwarding. The badge appears next to every sender name. Click any yellow or red badge to see the full signal breakdown.

Try AgentProof free →