Desktop, webmail, mobile and Image Cache categories defined

The email clients tracked via Email Analytics will fall into one of four platforms or categories: Desktop, Webmail, Mobile or Image Cache. Here's how we define these categories:


These email clients are installed software that is viewed by opening a program on a Mac or Windows PC. Email addresses from a variety of service providers (corporate/business domains as well as free services) can be viewed in desktop clients via IMAP or POP. This includes Outlook, Lotus Notes, Apple Mail, and Thunderbird.


These email clients are viewed in a web browser (Internet Explorer, Firefox, Chrome, Safari, etc.) and generally provide email services to the public free of charge. Examples include, and Prior to August 4, 2023, this also included Gmail,, Yahoo! and AOL. After August 4, 2023 these email clients report under the Image Cache category.

NOTE: Webmail opens made on smartphone browsers will be classified under the mobile category (i.e. using Android). See below for more details.


This category includes email opens made via a smartphone or tablet, for example, iPhone, Android, Blackberry, iPad, Kindle.

Mobile platform specifics

Opens tracked on smartphones and tablets are classified as a mobile open in your reports, regardless of the specific application used to open the email. In addition, webmail opens on smartphones (opens made outside an application, but still in the web browser on the device) are also classified as mobile opens.

Opens tracked for smartphones could appear in two different ways in your reports based on how the opener accessed the email via their device:

  1. Opens made via the default Mail app on a device will show up as that device (i.e. Android).
  2. Opens made via some third-party apps, or with the mobile browser on a smartphone can be reported as a subset of webmail opens (i.e. using Android), or as the default/native mail client.

Take an + Android user for example. If a user stored their account settings to open in the Mail application on their Android, the opens will appear under the main Android category. If the user opened the mobile browser on their Android, and checked their email by logging into, this open will appear as using Android. Both types of smartphone opens, as well as Kindle/iPad webmail opens, will be listed in the mobile segment and have a platform category of mobile.

Various mobile applications may report differently, depending on how the application was built.

Image Cache

This category was added August 4, 2023 to account for the email clients that use a common proxy to cache images. This includes Gmail, Yahoo and AOL. Apple Mail Privacy Protection also uses image caching. For opens on these email clients we cannot determine email client version or whether the platform was webmail or mobile.

Did this answer your question? Thanks for the feedback There was a problem submitting your feedback. Please try again later.

Still need help? Contact Us Contact Us