unfortunately, it's not possible to attach files into tasks. You could add emails as tasks using our Chrome plugin
or add tasks via email (detailed information can be found after clicking on the envelope icon in the top-right cornet of your task lists in a project view), but you can't upload any files within tasks.
If you'd like to add files into tasks and are working in a team, you could try our Project Management tool - Wedoist: https://wedoist.com
Still, thank you for your feedback, we appreciate it and will consider adding such feature in future development. You're welcome to vote for these requests in our Votebox: