Our spam filter combines two layers: an email filter that catches throwaway addresses and signup-evasion tricks, and a traffic filter that blocks requests from networks heavily associated with abuse — VPNs, proxies, Tor exits, datacenters, crawlers and more. Each layer can be tuned independently per site.
Spam Filter
Our advanced Spam Filter uses state-of-the-art AI technology to identify and block unwanted messages, comments, and form submissions with unprecedented accuracy. Designed for modern digital businesses, our solution adapts to evolving spam tactics in real-time.
The Prosopo Spam Filter can be seamlessly integrated into websites, applications, and communication channels to ensure only legitimate content reaches your users and systems. With minimal false positives and intelligent learning capabilities, it provides maximum protection with minimal maintenance.
Why our Spam Filter is superior
Our AI-driven approach delivers unmatched accuracy while preserving legitimate user interactions.
Advanced AI detection
Unlike traditional keyword-based systems, our AI analyzes content patterns, sender behavior, and contextual signals to identify sophisticated spam attempts.
Customizable protection levels
Set protection thresholds based on your needs - from permissive for general content to strict for sensitive channels.
Email pattern rules
Catch the most common evasion techniques out of the box, including the Gmail dot/+tag trick where one mailbox poses as dozens of distinct addresses. Add your own regex patterns for organisation-specific abuse.
Traffic filtering
Block submissions by connection type — VPN, proxy, Tor, datacenter, crawler, and more — each with its own independent toggle. Abusive networks are blocked by default for every account.
Simple integration
Implement with just a few lines of code through our API or use our pre-built plugins for popular platforms like WordPress, Shopify, and more.
The benefits of choosing Prosopo Spam Filter
Catches the patterns spammers actually use
Curated default rules block the Gmail dot trick, random plus-tag suffixes, and other common signup-spam evasion techniques out of the box.
Self-learning system
Our spam filter continuously improves by learning from new spam patterns and administrator feedback.
Real-time protection
Instant scanning and filtering ensures spam never reaches your users or systems.
Multi-channel coverage
Protect comments, contact forms, user-generated content, and communication systems with a single solution.
Detailed analytics
Gain insights into spam patterns and attack vectors with comprehensive reporting tools.
How Prosopo Spam Filter works
The Spam Filter sits in front of your verification step and rejects requests that already look abusive before any further processing happens. It works in two layers — Email Filter for fake or disposable addresses, and Traffic Filter for abusive network sources — and each can be tuned independently per site.
Email Filter: stop signup spam
Most signup spam doesn't come from random email accounts. It comes from a small set of evasion techniques that turn a single mailbox into thousands of apparent addresses, or from networks of disposable inboxes that exist only to bypass verification.
The Email Filter catches both:
- Gmail dot and plus-tag normalisation.
a.l.i.c.e@gmail.com,alice+abc@gmail.comandalice+xyz@googlemail.comall resolve to the same Gmail inbox. The filter optionally normalises Gmail addresses before applying your rules, so one rule catches every variant. - Maximum-dots threshold. Limits the number of dots allowed in the local part of an address — effective against the Gmail dot trick.
- Curated default patterns. A maintained ruleset that targets common signup-spam tactics like random plus-tag suffixes and excessive-dot local parts.
- Custom blocklist. Add your own patterns to block addresses unique to abuse you're seeing.
- Disposable-domain detection. Optionally rejects addresses from known throwaway providers — and follows the domain through redirects, CNAMEs and MX records so freshly-registered throwaway domains can't slip through by pointing at a known backend.
Traffic Filter: block abusive network sources
The Traffic Filter rejects requests by the type of network they came from. Each filter is an independent toggle, so you can build the exact policy your audience needs:
| Filter | What it blocks | Recommended for |
|---|---|---|
| Abusive networks | Networks with a strong abuse signal | Everyone — on by default for all accounts |
| VPN | Known consumer VPN services | Sites with high signup-fraud exposure |
| Proxy | HTTP, HTTPS and SOCKS proxies | API endpoints and high-value forms |
| Tor | Tor exit nodes | Most consumer-facing forms |
| Datacenter / Hosting | Cloud and hosting IP space | Sites whose users browse from residential networks |
| Crawler | Known automated bots | Most forms (excluding documentation/marketing pages) |
| Mobile | Cellular networks | Niche — only when fixed-line access is required |
| Satellite | Satellite internet | Niche — only when ground-based access is required |
Blocks are reported back to your application with a distinct reason for each filter, so you can show users a tailored message ("Please disconnect your VPN and try again", "This form isn't supported over Tor", and so on) rather than a generic failure.
Built for both ends of the spectrum
- Free tier accounts get abusive-network blocking enabled by default — the single highest-signal filter, on without any configuration.
- Professional and Enterprise unlock every other filter and the Email Filter, with per-site tuning, custom regex patterns and Gmail normalisation.
How Prosopo Spam Filter compares
| Prosopo Spam Filter | Akismet | reCAPTCHA / hCaptcha | |
|---|---|---|---|
| Network-level blocking (VPN, Tor, datacenter) | ✓ | ✗ | ✗ |
| Gmail dot / plus-tag normalisation | ✓ | ✗ | ✗ |
| Disposable-domain detection (follows redirects, CNAMEs, MX) | ✓ | Limited | ✗ |
| Custom regex blocklist | ✓ | ✗ | ✗ |
| Per-block reason codes for tailored user messages | ✓ | Limited | ✗ |
| GDPR-compliant data handling | ✓ | Varies | ✗ |
Common use cases
- Stop credential stuffing — block disposable inboxes used to enumerate accounts.
- Prevent phishing campaigns — reject signups from networks tied to known abuse.
- Defend signup forms — catch the dots-and-tags tricks used to bypass per-email rate limits.
Configuration reference
Full details of the Email Filter rules, the eight Traffic Filter toggles and their block reasons are in the docs:
Request a Demo of Prosopo Spam Filter
Our Spam Filter technology is available as both a standalone product and part of our Enterprise suite. Contact our sales team for pricing options.
Trusted by companies of all sizes
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- 1B+
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- 100M+
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Frequently Asked Questions
How does the spam filter work?
Will legitimate messages be blocked?
Defaults are tuned to minimise false positives — the curated email patterns target known evasion tricks rather than legitimate names, and the only traffic filter enabled by default targets networks with a strong abuse signal. Every filter is independently toggleable, so you can dial sensitivity to your audience.
Can the spam filter be integrated with our existing systems?
Yes, our spam filter offers flexible integration options including REST API, JavaScript snippets, server-side modules, and pre-built plugins for popular platforms. Our technical team can assist with custom integrations for proprietary systems.
Does the spam filter work for non-English content?
Yes. The email and traffic filters are language-agnostic — they look at addresses, domains and network properties rather than message text — so they work the same for content in any language.
Can you stop the Gmail dot trick (e.g. <code>a.l.i.c.e@gmail.com</code> vs <code>alice@gmail.com</code>)?
Yes. The Email Filter ships with a curated default ruleset for this exact pattern, plus a configurable maximum-dot-count threshold for the local part of an email address. You can also opt in to Gmail address normalisation, which strips dots and +tag suffixes before evaluating your custom regex blocklist — so a single rule catches every variant of the same Gmail mailbox.
Can I block submissions coming from VPNs, proxies, or Tor?
Yes. The Traffic Filter provides independent toggles for blocking VPN, proxy, Tor, datacenter, crawler, mobile and satellite traffic. Each block returns a distinct reason so your application can show the user a tailored message — for example asking VPN users to reconnect, or telling Tor users the form isn't supported on that network.
Are abusive networks blocked automatically?
Yes. Traffic from networks flagged for abuse is blocked by default for every account, including free tier. Paid-tier accounts can adjust this setting, but it is recommended to keep it enabled.
What traffic types can I filter?
The Traffic Filter supports eight independent filters: VPN, proxy, Tor, abusive ASNs, datacenter/hosting IPs, crawlers, mobile networks, and satellite connections. Each can be toggled on or off per site. Traffic filtering is a paid feature, except for abusive network blocking which is enabled for all accounts.
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