Email domain
An email domain is the part of an email address that appears after the @ symbol, identifying the organisation or email service associated with the account. In the address marketing@spotler.com, ‘spotler.com’ is the email domain. The domain is what receivers’ mail systems use to look up the DNS records responsible for delivering mail, including MX records (which server handles incoming email), SPF records (which servers are authorised to send outgoing email), DKIM keys, and DMARC policies. In this sense, the email domain is the foundational identity asset in email authentication.
The domain from which you send marketing emails matters for deliverability in two interconnected ways. First, the reputation of your sending domain is tracked by inbox providers and contributes to whether your emails reach the inbox. Second, your domain’s DNS records determine whether your emails pass authentication checks (SPF, DKIM, DMARC), which are increasingly required by major inbox providers for reliable delivery. A domain with a strong sending history and correctly configured authentication records sends signals of trust and legitimacy.
Many B2B senders use a separate subdomain for marketing email rather than their primary corporate domain, for example, news.company.com instead of company.com. This protects the root domain’s reputation from any deliverability issues that arise from marketing sends and allows the marketing programme to build its own sending history. Whether to use a root domain or a subdomain depends on your sending volume, your existing domain reputation, and your ESP’s recommendations.
What is the difference between an email domain and an email address?
An email address is the complete identifier used to send and receive email, consisting of a local part (before the @ symbol) and a domain (after it). For example, in sophie@spotler.com, ‘sophie’ is the local part and ‘spotler.com’ is the email domain. The domain is the organisational identifier that links the address to the infrastructure responsible for email handling. Multiple email addresses can share the same domain.
Should I use a subdomain for sending marketing emails?
Using a sending subdomain (such as mail.yourdomain.com or news.yourdomain.com) for bulk marketing email is recommended practice for many organisations. It separates the reputation signals from your marketing sends from those of your corporate email, protecting your primary domain’s standing if a marketing campaign triggers deliverability issues. It also allows you to build a distinct sending reputation for your marketing programme. Your email service provider can advise on whether your specific sending volume and programme type warrants a subdomain setup.
Why is the email domain important for deliverability?
Inbox providers use your sending domain as a key identity signal when evaluating incoming messages. They track the historical reputation of your domain: how often emails from it generate spam complaints, how often they bounce, how consistently they are authenticated, and whether the domain has been associated with phishing or spam activity. A domain with a strong positive history enjoys better inbox placement. A domain with a poor reputation, or one that has been recently set up with no sending history, may face filtering or blocking until it builds a track record.