Use this data to further personalize email campaigns. For example, use your open tracking reports to send a new email campaign with the Subject "Save 20% on next brownie order - for iPad users only" to just the people that opened your last email campaign with an iPad.
To access "email client" reporting data, to Reporting and then go to Opens from either your broadcast email campaign reports or your transactional email reports.
Transactional Email Opens Sample: See how many of each email client type was used to open emails in a specific Transactional Email Group.
Broadcast Campaign Raw Open Tracking Data: See exactly what email client was used to open the email for each recipient. Includes the technical Browser-Agent as well as the friendly name of the email client.