We have few users who have logged onto qlikview server through their desktop to acquire a CAL licence. After that generally the users can open any file from their desktop versions. In this scenario.... the users are still not able to open the files shared with them over emails.
Open the Qlikview desktop version from users desktop -->Go to Getting started --> and check the license information. It should say "Leased license" when you borrow a license from QV server, else you would not be able to open the applcaiton which is developed by others.
1) User is not able to open any of the file or a particular file?
2) User connected the QV server via QV desktop and viewed the files or from the browser?
3) CAL might also get assigned when a user try to access the QlikVeiw file from the browser. it has happen to many of my user also. Check the user desktop version has the valid license (desktop -->Go to Getting started --> and check the license information. It should say "Leased license")