How do blocklists detect cold domains?

Cold domains (newly registered domains with no sending history) face immediate suspicion from blocklists because spammers frequently burn through disposable domains. Several blocklists specifically target or heavily weight domain age as a risk factor.

How cold domains get detected:

• Day Old Bread (DOB): Spamhaus DBL specifically lists domains less than 24 hours old appearing in email. The assumption: legitimate senders don't launch new domains into immediate email campaigns.
• Domain age scoring: Many filters add spam points for domains registered recently (typically under 30 days)
• Whois data analysis: Registration patterns, registrar reputation, and nameserver choices associated with spam domains
• Behavioral analysis: New domain suddenly sending volume without warmup history triggers alerts

Why cold domains are risky for blocklists:

• Spammers register domains, blast them, and abandon them when blocked
• No sending history means no reputation - filters default to suspicion
• Legitimate senders typically don't launch email from brand-new domains
• Domain age is a simple, effective filter that catches most throwaway spam domains

How to use new domains safely:

1. Register early: Set up domains 30+ days before you need to send
2. Build presence: Create a website, establish DNS records, build a web presence
3. Warm gradually: Start with small volumes to engaged recipients
4. Proper authentication: Configure SPF, DKIM, DMARC before sending anything
5. Avoid cold domain patterns: Privacy registrations, cheap registrars, and nameservers associated with spam all add risk

Timeline for domain maturity:

• <24 hours: High risk, likely DOB listed
• 1-7 days: Still high risk, limited history
• 7-30 days: Moderate risk, building baseline
• 30+ days: Age no longer a primary factor (behavior takes over)

Blocklists view cold domains like a ship with fresh paint, no cargo history, and a crew that won't answer questions. You might be legitimate, but the profile matches pirates too closely for comfort. Establish your identity before sailing into busy waters.