When the Daleks dictate, its good to write what they tell you and hope that you arent signing up for a concentration camp. However, back in the first three episodes of their first story, they were considered a completely trustworthy race, so Susan (the companion of the time) decided to write a letter to the Daleks sworn enemies inviting them to the Dalek city with some obviously honest food as a lure. So Susan wrote her name at the bottom of the letter (read death sentence) and when the Daleks read it, they immediately suspected her of treachery. Or maybe they were just angry at her awful writing skills, as she made five letters take up a whole line like a childlike retard.