I worked for DHL in the 90's (security), I worked for Fed Ex before DHL in the early 90's and there was no comparison...Fed Ex blows DHL away and even considering technology had advanced by the time I was at DHL they were a decade behind easily.....not sure how it is anymore, I know DHL bought out Airborne and DHL is owned by the Dutche Post which is one of the wealthiest companies in the world....DHL was much bigger in Europe until they bought out/merged with Airborne.
I'm a little surprised though that they have overnight letter delivery problems and can't get an intl letter to customers in a professional manner...the overnight letter is easily the most simple delivery....I guess they are still trying to do everything cheaper.....the delivery industry profit margins have dropped over the past 10 years , with so much competition and the ever rising fuel costs....think about what 1 cent rise in fuel does to a company like DHL/UPS we're talking millions for every penny.
No matter what a mixed up overnight letter delivery is inexcusable in this day and age, and should happen less than 1% of the time.