Hi,
I ́m trying eM Client 7.0.26687.0. I try to configure “Frecuency” and “Preserve last” but when I click Apply an error appears (see the image). Then, the automatic backup never worked (It was never a zip file from the automatic backup).
The manual backup (Menu > File > Backup) functions well for all users, without problems. 
I ́ve studied and tested the situation in my sistem (Windows 10 Home with the Anniversary Update) and I could conclude that this is an issue that will have to be fixed.
The problem is: After installing eM Client in a PC with 1 Admin user account + 1 Standard user account, the FIRST user that configures scheduled backup will be the user in which the scheduled backup will work well.
After that, if other user try to configure scheduled backup, the above error will appear.
No matter if the account is Admin or Standar (I made the tests for checking that). This is because the program creates only one task associated to the account user ́s name; when the second user tries to activate the scheduled backup the eM Client doesn ́t create a new task for this user.
The development team should resolve this issue in order to permit the creation of all necessary Windows Tasks according to the backup demand of each user in a PC with multi-users.
I could import the Task (created for the first user) and export it as a new one, changing the user name but this task will no be linked with the “Frecuency” and “Preserve last” features of the user ́s configuration with the error, therefore this is not a correct way.
As possible buyer of a license, I would like that the eM Client perfectly works for all users of one PC.
I ́ll be waiting for your comments, thanks!