Everything old is new again. Whoever set up this message system restricted the types of associated files heavily, but they weren't nearly as cautious about individual characters, and the full old-fashioned character set includes all sorts of commands, some ordinarily used to construct new glyphs, some with broader applications. Sasha embeds an appropriate set of invisible commands in the subject line of one of the chain letters and forwards it from this personal account to a set of targets that include's Flute's accounts.