ESP (Email Service Provider)
An ESP is a service that sends email on your behalf. The term spans marketing platforms, transactional APIs, and cold outreach engines.
Product & Engineering · July 17, 2026 · 1 min read
An ESP (Email Service Provider) is any service that sends email on your behalf rather than from a personal mailbox. The term is broad: it covers marketing platforms, transactional APIs like Amazon SES, bulk senders, and cold outreach engines.
Because these categories make opposite assumptions about consent, volume, and deliverability, the ESP category you choose matters more than the specific product.
See the full guide: Related: what is an email sending platform.
Resources in this guide
| Type | Built for |
|---|---|
| Marketing | Opted-in newsletters |
| Transactional | App-triggered mail |
| Cold outreach | Personalized prospecting |
Frequently asked questions
Is an ESP the same as a cold email tool?
A cold email tool is one kind of ESP. The term also covers marketing platforms and transactional APIs, which are built for different jobs and should not be used interchangeably.
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