# Email service provider (ESP)

A service organization that provides transactional and marketing email services.

Most Email Service Provider (ESP) include features that allow customers to:

* Upload and maintain subscriber lists
* Schedule and send marketing campaigns
* Manage transactional email
* Improve email deliverability
* Monitor statistics of your email campaigns

ESPs also provide expertise to increase your [email deliverability][] and preserve your [sending reputation][]. To accomplish these goals, ESPs use features and tools like [Reverse DNS][].

An ESP might provide UI-based email services, [SMTP service][], or both. Twilio Email provides both.

[email deliverability]: /docs/glossary/deliverability

[sending reputation]: /docs/glossary/email-reputation-score

[Reverse DNS]: /docs/glossary/reverse-dns

[SMTP service]: /docs/glossary/smtp-provider