To believe that FedEx lacked knowledge of illegal activity, one must believe that they assumed some of these pharmacies were genuine and that while it was feasible to create special policies to ensure FedEx was paid, policies to verify the organizations legitimacy (which would also increase the chance of them being paid), were impractical. However, that will be difficult because one executive told another that: "...these types of accounts will always result in a loss at some point. They have a very short lifespan and will eventually be shut down by the DEA." (emphasis added)
They certainly can't argue, as many others in this thread have, that the companies weren't identifiable: They were doing it to enforce this policy. The credit department maintained a list of pharmacies that, at one time, had 600 entries on it.