Email service provider (ESP)

What is an email service provider?

An email service provider (ESP) is software that stores an email list and sends emails to it. Organizations use one to send newsletters, welcome emails, announcements, and automated follow-ups to the people who signed up. ESPs also handle the parts of email that are hard to do by hand: sign-up forms, unsubscribe links, bounce handling, and getting messages delivered to inboxes. Mailchimp, Kit (formerly ConvertKit), and ActiveCampaign are well-known examples.

The ESP is where most organizations' audience lives. It's the list they own and the place their follow-up happens.

How does it work?

An ESP holds contacts (often called an audience, list, or subscribers) along with details like name and sign-up date. Contacts get in through a few routes:

• Forms on a website or landing page, built in the ESP.
• Imports, such as uploading a CSV.
• Integrations, where another app adds contacts automatically through the ESP's connection or API.

Once someone is on the list, the ESP sends what the owner sets up: a one-off newsletter, a welcome email the moment they join, or an automated series over several weeks. It also manages consent tasks, such as unsubscribes and, if the owner turns it on, double opt-in confirmation.

Most ESPs organize contacts with labels such as tags, groups, or segments, so a list can be split by where people signed up or what they asked for. For anything without a direct integration, tools like Zapier or a webhook can pass contacts between apps.

Why it matters at live events

The point of collecting emails at an event is to follow up afterward, and the follow-up happens in the ESP. If contacts from a keynote or a booth sit in a spreadsheet for two weeks before someone imports them, the welcome email arrives when people have forgotten the talk.

Getting event sign-ups into the ESP right away fixes that. With Textiful, the contact goes to your tools as soon as someone finishes the flow. Textiful adds the contact to Mailchimp, Kit, ActiveCampaign, or HubSpot directly. Other ESPs and CRMs (Constant Contact, Keap, Salesforce, MailerLite, Google Sheets, and more) connect through Zapier's "New Contact" trigger.

Textiful starts the conversation at the event and hands off the contact; your email tool does the follow-up, under your name, to a list you own. See integrations for the current list.

Key takeaways

• An ESP stores your email list and sends emails to it, including automated follow-ups.
• Contacts arrive through forms, imports, or integrations with other apps.
• At events, getting sign-ups into the ESP right away means follow-up arrives while people remember you.
• Textiful adds contacts to Mailchimp, Kit, ActiveCampaign, and HubSpot directly, and to other tools through Zapier.

Try it at your next event → Start a free trial