What is an Email Service Provider (ESP)?
An Email Service Provider (ESP) is a company or platform that enables organizations to send, manage, and track email communications at scale. ESPs provide the infrastructure, authentication tools, and analytics needed for marketing campaigns, transactional messages, and automated workflows. Popular ESPs include SendGrid, Mailchimp, Klaviyo.
ESPs handle the technical aspects of email delivery, connecting to the SMTP network, managing IP reputation, and maintaining compliance with authentication protocols like SPF, DKIM, and DMARC.
When a business sends an email through an ESP, the service formats the message, routes it to mail servers, and ensures proper authentication. The ESP’s servers often handle millions of emails daily across thousands of domains, requiring strong infrastructure and deliverability expertise.
Typical ESP functions include:
When selecting an ESP, organizations should prioritize:
Using an ESP that fails to maintain proper authentication alignment can lead to delivery issues, domain reputation loss, or spoofing vulnerabilities.
DMARCeye provides complete visibility into how ESPs authenticate and send on behalf of your domain. By analyzing DMARC aggregate reports, the platform identifies which ESPs pass or fail SPF, DKIM, and DMARC alignment checks.
DMARCeye’s dashboards reveal misconfigured senders, weak authentication policies, and unauthorized third parties using your brand’s domain. It also helps verify that ESPs rotate DKIM keys properly, maintain valid SPF records, and align “From” headers with your domain policy.
With these insights, organizations can evaluate ESP performance, ensure compliance with authentication standards, and strengthen both deliverability and trust in every message sent through external providers.
Sign up for a free trial of DMARCeye today and secure your email domain.
To learn more about DMARC and DMARC-related terms, explore the DMARCeye Glossary.