Domain WHOIS Lookup

WHOIS data tells you everything about a domain's registration — when it was created, when it expires, who registered it, and which nameservers it uses. For email marketers, this matters because domain age is one of the signals ISPs use when evaluating sender reputation. A brand-new domain blasting 10,000 emails on day one looks like a spammer. A five-year-old domain with consistent sending history gets the benefit of the doubt.

What WHOIS reveals about a domain

A WHOIS lookup returns the registrar (where the domain was bought), creation date, last updated date, expiration date, registrant contact information (often redacted for privacy), and the nameservers handling DNS. The creation date tells you the domain's age. The expiration date matters too — a domain registered for one year looks more suspicious than one registered for five years. Nameservers tell you which DNS provider is being used, which can be useful when troubleshooting DNS-related email issues.

Domain age and email deliverability

ISPs treat new domains with suspicion because spammers constantly register fresh domains, blast emails, and abandon them. Most deliverability experts recommend waiting at least 30 days before sending marketing emails from a new domain, and using that time for email warmup. Domains less than 90 days old face significantly higher spam filtering rates. If you've just purchased a domain and need to send immediately, start with transactional emails to engaged users and gradually scale up volume.

Checking expired domains and purchased domains

Buying an expired domain for email marketing is risky. The previous owner might have used it for spam, leaving behind a damaged reputation and blacklist entries that now become your problem. Always run a WHOIS lookup on a domain before purchasing it to check its history. If the domain has been registered and dropped multiple times, that's a red flag. Pair this with a blacklist check and a domain reputation check to understand what you're inheriting.

Using WHOIS for email investigation

WHOIS is also valuable when you're investigating suspicious emails or verifying a sender's legitimacy. If someone claims to represent a major company but their email domain was registered last week, that's a phishing attempt. Similarly, if you're evaluating a potential partner or vendor, checking their domain age gives you a basic credibility signal. Combine WHOIS data with MX record lookups and SPF/DKIM/DMARC checks for a complete picture of a domain's email infrastructure.