Email service providers (ESPs) explained

At a glance: Create robust email campaigns with email service providers using OneLink branded links and deep linking.

Why use ESPs?

Email service providers enable running large-scale email campaigns so that you can: 

  • Acquire new users
    Your company generates leads through various channels. You can target those leads in email campaigns and convert them to mobile app users.
  • Convert existing users
    Send emails to all your desktop users and convert them to mobile app users.
  • Increasing user engagement
    On holidays and special occasions, you can send out promotions to your existing users to promote sales. You can use deep linking for a better user experience that increases the chance that users will end up making a purchase. 

Supported email service providers

ESP email campaigns for mobile app users can cause attribution and deep linking issues.

To overcome those issues and work with the ESPs, you must follow their exact integration steps.

Use the links in the table that follows to go to the article on the ESP you wish to use for email campaigns.

Email service providers









ESP deep linking challenges

iOS Universal Links

Implementing deep linking using Universal links

Developers need to associate their apps with specific domains to perform deep linking with Universal Links. This is a security measure in iOS (9 and above) that ensures that only specific domains can launch associated apps.

Developers that use the AppsFlyer OneLink solution associate OneLink domain with their app. When a user clicks on OneLink, it launches the app that is associated with it. The developer then gathers information from the AppsFlyer SDK for deep linking and customizing the user experience.

Issues with links in emails from ESPs


ESPs wrap links in emails with their own links. They do so in order to measure and report engagements. However, this practice could break the OneLink flow if not handled properly. The app doesn't launch and it results in a broken user experience.

Some ESPs support iOS Universal Links while wrapping the links with their own measurement links. Apps launch when users click on links in the emails. However, the OneLink flow still breaks which results in the following:

  • No measurement of engagements (clicks) on AppsFlyer end
  • App Launch is not attributed to a click
  • AppsFlyer SDK doesn't pass attribution data to the App developer

The solution by AppsFlyer


AppsFlyer joins forces with prominent ESPs in order to solve the problem with broken deep linking. The solution combines several technologies:

The combination of these technologies allows the SDK to resolve the underlying OneLink, even though it is wrapped in other links. As the SDK resolves the underlying OneLink, it is able to provide the developer with the necessary information for deep linking and customizing the user experience.

The following ESPs fully support AppsFlyer solution for deep linking with Universal Links in emails:

Other ESPs require some additional work during integration to ensure a smooth OneLink deep linking experience.  

Android App Links

Android developers might experience a similar problem with App Links. However, deep linking using URI scheme is still widely supported on Android. What this means is that developers can still use URI scheme to deep link from emails that are sent by ESPs.