Theory:Doctor Who television discontinuity and plot holes/Kerblam!


 * Runaway Bride established that entering the TARDIS is impossible unless connected to the TARDIS (like those particles in Donna) or the Doctor materialises around the object (as showcased in The Parting of the Ways,). So how does the 'Kerblam!' postman teleport aboard?
 * A junk mail robot does it in The Greatest Show in the Galaxy. Runway bride broke continuity, not this. And perhaps the shields were up.
 * That doesn't really explain how though? And Runaway Bride justified it as she had pariticles in her connecting them.
 * Maybe after the Doctor recognised it as a teleport pulse, remembered she ordered something and temporally let the shields down to allow the Kerb!am Man to teleport in.
 * The TARDIS let her shields down herself perhaps? The TARDIS knew it was someone asking for help rather than a threat.
 * Since the Doctor ordered the fez herself, she would have organised for the TARDIS to allow the package to come through.