The term user agent stands for agent software, which is acting on behalf of a user. In its most common meaning, it is a client application that uses a particular network protocol.

When a user agent operates inside a network protocol, like HTTP, SIP, and NNTP, it identifies itself (including the operating system and software vendor) by submitting an identification string to the operating peer.

This video produced by OSINT Curious considers the user agent string and explains why you should care about it.

User Agents in Email Marketing

When it comes to email marketing, a user agent serves as an essential source of information about operating systems, browsers, and devices, which subscribers use to open emails. SendPulse provides these statistics for all email campaigns.

Campaign statistics by devices

Knowing these statistics enables you to analyze an email campaign in terms of graphic design and adapting HTML emails to different kinds of mobile devices. 


  1. The article "User agent" on Wikipedia explains what a user agent is and considers its usage.
  2. The article "User Agent" on MDN web docs examines the user agent string in different browsers.
  3. The article "User Agent: Learn Your Web Browser’s User Agent Now" on WhoIsHostingThis defines a user agent, states its types, and considers HTTP user agent strings.
  4. The article "What Is a Browser’s User Agent?" on How-To Geek defines a user agent, explains how to examine and use them.
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