# 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 the following:

* [Reverse DNS](/docs/sendgrid/glossary/reverse-dns/)
* [Dedicated IPs](/docs/sendgrid/api-reference/ip-address/add-ips)
* [IP warming](/docs/sendgrid/concepts/best-practices/warm-up-ip-addresses)

An ESP might provide UI-based email services, [SMTP service](/docs/sendgrid/glossary/smtp-provider), or both. Twilio SendGrid provides both.

[email deliverability]: /docs/sendgrid/glossary/deliverability

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