Business plans don't come much more boring than the shipping of letters and parcels that Royal Mail (LSE: RMG) does. While the long-term decline of posting letters continues, the rise of online shopping has created a rapidly expanding market for the shipping of parcels. However, Royal Mail isn't the only player in this field and margins have been squeezed as international competitors and the likes of Amazon move to gain market share. Although Royal Mail increased UK parcel volumes by 4% over the past nine months, revenues only bumped up 1%.