We've recently upgraded to Cognos Analytics and this is one of our critical griefs with the latest version. There are number of key reports that get emailed everyday and most of the Execs use their phones to look at the numbers. IPhone being one of a widely used device, with the latest upgrade to Cognos 11, IBM has stopped supporting the mail clients on iOS devices. Thereby, when a user gets a report (in HTML format) via email, all they see is a blank page within the email.
IBM apparently is aware of this issue and has not planned a fix yet on this. There is a RFE open for this and voting is open for this. If your users use iOS devices and view emails within them, please vote so that we can raise up the priority of this RFE.
https://www.ibm.com/developerworks/rfe/execute?use_case=viewRfe&CR_ID=102186
Please note that you'd need to be logged in with your IBM id