I paid for my premium account but still cannot assign tasks via email. Thanks.
according to our database you have an active Premium account until August 25, 2013.
Please log out, clear your browser's cache and offline storage data, reload the browser and log back in directly to todoist.com.
Next, try to use any other Premium feature such as adding notes to tasks or in-task q: search and let me know if they work. As for sending tasks via email, please make sure that ti send a task via email, you're using the same email address as the one you've used to sign up for Todoist or, if you wish to use others, that they're added on the list of accepted addresses (at the bottom of the window from which you get the unique project's email address).