What is the difference between ESP and SMTP provider?

ESPs (Email Service Providers) offer complete email marketing platforms: campaign design, list management, scheduling, analytics, compliance features, and delivery. They're business solutions for marketing teams. **Mailchimp**, **Klaviyo**, and **Brevo** are ESPs.

**SMTP** providers offer infrastructure: servers, IP addresses, and connections for transmitting email. They focus on delivery mechanics rather than marketing features. **Amazon SES**, **Mailgun**, and **SparkPost** function primarily as **SMTP** providers, though some add marketing features.

Many senders use both: an **ESP** for marketing campaigns with rich features, plus an **SMTP** provider for **transactional email** needing high-speed delivery. The distinction isn't always sharp; some providers offer both capabilities. Choose based on whether you need marketing tools or infrastructure capacity.