On average, our mailings are opened by at least 60% of recipients using an "Unknown" email client. Gmail makes up for 20%, AppleMail is 10%, with the rest in small amounts. Has anyone else had this experience? I'm wondering if our audience is using obscure email clients or if older versions of Outlook are not being read as Outlook opens. Half of our list has university email addresses, and I'm guessing many of these use that client.