How does contact categorization work?
Cleanbox automatically assigns a category to each contact based on the sender domain. This helps you organize your inbox and build powerful filter rules without manual sorting.
How it works
When a new contact is created (the first time someone emails you), Cleanbox extracts the registered domain from the sender address using a public suffix list. For example:
order-update@shipping.amazon.com→ registered domain:amazon.comnoreply@accounts.google.com→ registered domain:google.com
This registered domain is then looked up in a curated database of domain-to-category mappings. If a match is found, the category is automatically assigned to the contact.
Freemail domains are skipped
Domains like gmail.com, outlook.com, yahoo.com, and other freemail providers are not categorized. A contact sending from john@gmail.com could be anyone — categorizing them by domain would be meaningless.
The 20 categories
| Category | Typical senders |
|---|---|
| Social Networks | Facebook, Instagram, LinkedIn, X, TikTok |
| Shopping | Amazon, eBay, Etsy, Zalando |
| Entertainment | Netflix, Spotify, YouTube, Disney+ |
| Finance | Banks, PayPal, Stripe, crypto exchanges |
| Travel | Airlines, Booking.com, Airbnb, Uber |
| Education | Universities, Coursera, Udemy, Duolingo |
| Food Delivery | Uber Eats, DoorDash, Deliveroo, Thuisbezorgd |
| Logistic Services | FedEx, UPS, DHL, PostNL, DPD |
| Business Services | Slack, Notion, Salesforce, HubSpot |
| News & Magazines | NYT, Reuters, Medium, Substack |
| Gaming & Gambling | Steam, Epic Games, PlayStation, Xbox |
| Internet & Communication | ISPs, Discord, WhatsApp, Zoom |
| Discounts & Promotions | Coupon sites, deal aggregators, cashback services |
| Restaurants & Dining | OpenTable, restaurant chains, food review sites |
| Events & Tickets | Ticketmaster, Eventbrite, Meetup |
| Productivity & Tools | GitHub, Trello, Figma, Jira |
| Hobbies & Interests | Reddit, forums, hobby platforms |
| Home & Supplies | IKEA, Home Depot, hardware stores |
| Fun & Activities | Theme parks, activity booking, games |
| Adult | Age-restricted content and services |
Manual category assignment
If a contact was not automatically categorized (because their domain is not in our database), or if you want to override the detected category, you can manually assign one from the contact detail page.
Using categories in filters
Categories become especially powerful when combined with filter rules. You can create filters that match on category, for example:
- Deny all emails from Discounts & Promotions senders
- Move Shopping emails to a dedicated folder
- Flag all Finance emails as important
- Mark Social Networks notifications as read on delivery
This lets you build broad rules that automatically apply to any sender in a category — even future contacts you have not seen yet.
Growing the database
The domain-to-category mapping database is continuously expanded. As more users connect their mailboxes, Cleanbox learns about new services and domains. Categories are assigned based on the service behind the domain, not on email content — so categorization is instant and does not require reading your emails.
