Merge command: [httpuseragent ]
Merge variable/item: mailHTTP_User_Agent

Comments:
CGI variable with info about the users web browser from which the reaction form(responder) was submitted.

Formula:
@text(mailHTTP_User_Agent)

Example:
Mozilla/5.0 (iPhone; CPU iPhone OS 13_3 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) GSA/89.2.287201133 Mobile/15E148 Safari/604.1