Create a report with an SSAS data source. The data source should be setup as follows:
1. Check "credentials stored securely" and enter some credentials
2. Check the "Use as Windows Credentials" checkbox
3. Check the "Impersonate the authenticated user" checkbox
Behind the scenes when running the report live, when you check the "Impersonate the authenticated user" checkbox, it appends the EffectiveUserName property to the connection string.
Now go to the subscriptions tab and click "New Subscription". You will get this error message:
Subscriptions cannot be created because the credentials used to run the report are not stored, or if a linked report, the link is no longer valid.