Your email tracker is lying to you.
Signum is the only tracker that filters Apple Mail Privacy prefetches, blocks bot traffic across six layers, and tells you who actually read your email.
Built for sales teams who send real email
Every other tracker counts
Apple MPP as a read.
Apple Mail Privacy Protection fires your tracking pixel before the recipient ever sees the email. Mailtrack, HubSpot, Streak, Mixmax — they all show this as an 'open.' That's why your open rates look like 90% and your replies look like 2%.
- 0sEmail sent
- 1.4sMPP prefetches pixel
- 1.4s✓ Pixel fired — marked OPENED
- 6h laterRecipient still hasn't seen email
- 3 daysNo reply. Why did they ghost?
- 0sEmail sent
- 1.4sMPP prefetch detected
- 1.4s✗ Flagged Apple 17.0.0.0/8 — not counted
- 4h later6 signals fire from iPhone in Mumbai
- 4h later✓ CONFIRMED · score 87 · human read
We use the same six signals as everyone else, then we filter the noise. What you see is what your recipient actually did.
We don't trust the pixel.
We don't even trust five signals.
Each signal fires from a different system in the recipient's email client. When all six corroborate, we know. When only one fires, we say so honestly.
Pixel GIF
A 1×1 transparent image. The classic. Fires when the email renders.
Most clients block it, MPP fakes it. We use it as ONE signal among six, never alone.
CSS Beacon
A stylesheet load. Independent network call, different cache rules than the pixel.
Fires even when image loading is disabled. Hard to fake without rendering the email.
Font Beacon
A @font-face declaration. Loads on layout, not on image fetch.
Survives clients that aggressively block images. Triple-confirmation when all three passive signals fire.
DNS Wildcard
A subdomain lookup. Weakest signal but fires from clients that block everything else.
Cannot be cached by image proxies. Last-resort confirmation that the email reached a real DNS resolver.
Link Click
Active engagement. The recipient deliberately moved their cursor and clicked.
Bot click bursts (3+ links in 2s) are filtered as SEG URL detonation, not counted as human.
Gmail API
Ground truth. The Gmail API directly reports the message was opened.
Requires the Workspace Addon. When it fires, score jumps to 90+. No bot can fake this.
FORMULA score = pixel + css + font + dns + click(capped 60) + api − deductions, clamped 0–100
Most opens aren't people.
Security scanners, link expanders, MPP prefetches, Microsoft Defender, Mimecast — they all open your email before your prospect does. We catch them at six different layers.
UA Blocklist
GoogleImageProxy, MailScan, SymantecScannerUA Anomaly
Firefox+Chrome combined, empty UA, headless markersIP Classifier
Apple 17.0.0.0/8 (MPP), Google proxy rangesTiming Window
Pixel fires under 3000ms — pre-fetch or scanClick Burst
3+ distinct URLs in 2s — SEG URL detonationHoneypot
display:none link clicked — only a bot wouldThree teams. Same problem.
Whether you're closing a Series A, a $500K MRR pipeline, or a $50M LP fund — accurate engagement data is the difference between focused work and shadow-boxing your inbox.
Stop guessing who replied to your cold outreach.
When you're 47 emails into a fundraise, you need to know which 3 investors actually read the deck — not which 47 inboxes Apple prefetched.
Your "opened" column is wrong by 40%.
SDRs spend their first hour every morning chasing fake opens. Signum gives them a sorted list of recipients who actually engaged, with confidence scores.
Know which LPs read the quarterly letter.
IR teams send the same letter to 200 LPs and have no idea who read it. Multi-signal detection plus document tracking gives you per-LP engagement depth.
Simple plans. No seat tax.
Build your engagement engine for the cost of one bad lunch. Annual plans save two months.
Free
For first-time tracking- 200 tracked emails / month
- Six-signal detection
- Six-layer bot filtering
- Single user
- Dashboard + Chrome Extension
Pro
For sales pros and founders- Unlimited tracked emails
- Workspace Addon (native Gmail)
- Real-time notifications
- Follow-up rules with score branching
- Document tracking + heatmaps
- Priority email support
Top
AI-augmented engagement- Everything in Pro
- AI-generated follow-up drafts (Claude)
- AI persona learning from your style
- Score-aware auto-reply suggestions
- Domain health monitoring
- Slack / Teams integration
Teams of 5+ · Talk to us about Enterprise
The questions everyone asks.
No. We use two distribution channels: a Chrome Extension that adds a Signum toggle to the Gmail compose UI (read-only DOM observation), and a Workspace Addon that uses Google's sanctioned APIs. The Workspace Addon is reviewed and approved by Google.
Mailtrack uses a single tracking pixel and counts every fire as an open. HubSpot does the same with light filtering. Signum uses six independent signals and runs every event through a six-layer bot detection cascade before counting it. You get score-based truth, not pixel-based noise.
Every tracked email includes a visible opt-out link in the footer. Recipients can opt out workspace-wide or globally with one click — no account required. We never sell data and never share tracking data outside your workspace. Our privacy policy covers GDPR and India's DPDP Act.
Currently we focus on emails composed directly in Gmail. For bulk cold email tooling, you should use the platform's built-in tracking. We're evaluating BCC tracking and SMTP relay options for V2.
Our score is bounded by what the recipient's email client allows. When the Gmail API (via the Workspace Addon) confirms a read, we hit 90+ with near-certainty. When only the pixel fires, we score 20 and mark it LIKELY. We never claim certainty we don't have.
Postgres database on Neon (US-East). Document files on Cloudflare R2. Email tracking ingest on Cloudflare's global edge. All sensitive fields (recipient email, subject, IP) are encrypted at the application layer using per-workspace keys derived from a master pepper stored in GCP Secret Manager.
Yes. From Settings → Data → Export, you can download all your tracked emails, recipients, and events as a JSON archive. Delete is also self-serve, with a 24-hour grace period in case of mis-clicks.
Axiom Tech Lab — a small, focused team in Bengaluru, India. We've been building B2B SaaS for 4+ years. Signum is our flagship product.
Stop guessing.
Start knowing.
Free for your first 200 emails per month. No credit card. No "verified by" footer. Real engagement data, finally.
Built in Bengaluru · Used by founders, sales pros, IR teams · v1.0