Each communication device currently, as default, displays posts as made by your character's name, as it appears in the game tag. So, Delta's posts will say they were made by "Delta."

Only characters with the communications expertise can change the display name - so if Delta wanted to make his say something else (leprechaun, etc.), he would either have to gain the communications expertise or find someone who has to do it for him. We'll update the post to include that!