sp am ▁market ▁in ▁ 2 0 0 3 , ▁one ▁of ▁the ▁growing ▁weak ness es ▁of ▁modern ▁anti - sp am ▁systems ▁was ▁that ▁of ▁" false ▁posit ives " ▁- ▁legit imate ▁mail ▁being ▁incorrectly ▁filtered ▁off ▁into ▁a ▁user ' s ▁J unk ▁mail ▁folder . ▁ ▁Red uc ing ▁false ▁posit ives ▁in ▁sp am ▁filters ▁became ▁the ▁focus ▁of ▁Ge oby tes ' ▁anti - sp am ▁product ▁strategy ▁as ▁the ▁company ▁saw ▁this ▁problem ▁causing ▁considerable ▁incon ven ience ▁and ▁cost ▁to ▁business es ▁and ▁other ▁email ▁users . ▁ ▁Ge oby tes ▁subsequently ▁invent ed ▁two ▁new ▁techn ologies ▁aim ed ▁at ▁reducing ▁false ▁posit ives ▁in ▁sp am ▁filters ▁- ▁Case Keys ▁and ▁Sp amb order . ▁ ▁Case Keys ▁▁ ▁Case Keys ▁technology ▁effectively ▁implements ▁a ▁“ Sender ▁Author ization ▁System ” ▁without ▁the ▁need ▁for ▁any ▁special ▁software ▁or ▁action ▁to ▁be ▁installed ▁or ▁performed ▁by ▁the ▁sender . ▁Pre viously ▁such ▁systems ▁would ▁require ▁a ▁user ▁to ▁authentic ate , ▁install ▁special ▁software , ▁or ▁to ▁be ▁previously ▁know ▁to ▁the ▁system . ▁Additionally , ▁traditional ▁systems ▁do ▁not ▁recover ▁well ▁from ▁a ▁comprom ised ▁‘ key ’ . ▁Case Keys ▁avoid s ▁or ▁mit ig ates ▁all ▁of ▁these ▁legacy ▁problems . ▁ ▁In ▁its ▁simplest ▁form , ▁Case Keys ▁is ▁a ▁system ▁that ▁uses ▁a ▁combination ▁of ▁lower ▁and ▁upper ▁case ▁letters ▁to ▁encode ▁email ▁addresses ▁with ▁a ▁unique ▁key . ▁An ▁example ▁might ▁be : ▁ ▁My Em