Do-not-contact list: what it means
A do-not-contact (DNC) list is a suppression list of people, email addresses, domains or companies your team must never prospect. It typically holds anyone who asked not to be contacted, unsubscribed or bounced, plus existing customers, open deals and partners. Every send is checked against it first.
What belongs on it
| Entry | Match on | Why |
|---|---|---|
| People who said no or asked to be removed | Email, LinkedIn URL, phone | Legal and basic courtesy |
| Unsubscribes | Required by most email laws and by Gmail and Yahoo for bulk senders | |
| Hard bounces | Protects bounce rate | |
| Customers | Company domain | Do not cold-pitch people who already pay you |
| Open deals | Company domain | A colleague is already talking to them |
| Partners, investors, competitors | Company domain | Awkward at best |
Matching on more than one identifier matters. Someone who said no on LinkedIn should not then get a cold email.
A worked example of domain matching
Say your CRM has 300 customers. 280 use company addresses like jo@brightdental.co.uk. Suppressing brightdental.co.uk stops anyone at Bright Dental being prospected. Good.
The other 20 customers signed up with personal addresses, including sam.lee@gmail.com. If your suppression logic takes the domain from every customer email, you have just suppressed every Gmail user on earth. Your next list of local businesses, half of whom use Gmail, silently drops to nothing.
The rule: suppress by company domain only for business domains. For free email providers, suppress the exact address.
How to keep it current
- Sync from the CRM, not a spreadsheet export. Customers and deals change weekly.
- Write to it automatically from replies. A "not interested" reply should add the person without anyone remembering to do it.
- Check before you spend. Filter against the list before paying for data enrichment, not just before sending.
- Share it across tools and teammates. A list in one tool does not protect sends from another.
Common mistakes
- One list per tool. People fall through the gaps between them.
- Suppressing free email domains whole, as above.
- Only suppressing at send time. You still paid to find and enrich people you can never contact.
- Removing people to hit volume targets. Once someone asks to be left alone, that is permanent.
Related terms
The DNC list is the stop rule behind every email sequence, and a core part of email deliverability: contacting people who opted out is a fast route to spam complaints.
How Sluice handles it
In Sluice a "no thanks" reply adds the person to the do-not-contact list, and sequences stop on it. With HubSpot connected, customers, open deals and customer companies come back from HubSpot and are never cold-pitched, and a customer on free mail like gmail does not suppress everyone on gmail. HubSpot is the only CRM integration so far.
Questions people ask
- What is the difference between a do-not-contact list and an unsubscribe list?
- An unsubscribe list holds people who opted out of email. A do-not-contact list is wider: it can include customers, partners, competitors and people who said no on any channel, and it applies to every channel.
- Should I suppress whole domains?
- For customers and competitors, usually yes, because you do not want anyone at that company getting a cold pitch. Never suppress free email domains such as gmail.com as a whole.
- How long should someone stay on a do-not-contact list?
- If they asked not to be contacted, indefinitely. For customers and open deals, for as long as the relationship lasts, which is why syncing it from your CRM is better than a static file.
Sources
Try it on your own market
Sluice quotes the worst-case price before anything runs and charges only for lookups that found something, so finding out costs close to nothing.
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