Prince Philip, Duke of Edinburgh visit the Queen Elizabeth II delivery office in Windsor with Prince Philip, Duke of Edinburgh on April 20, 2016 in Windsor, Britain. The visit marks the 500th Anniversary of the Royal Mail delivery service. The Queen and Duke of Edinburgh are carrying out engagements in Windsor ahead of the Queen's 90th Birthday tommorow. REUTERS/Chris Jackson/Pool

WINDSOR, ENGLAND - APRIL 20: Queen Elizabeth II meets postmen as she visits the Queen Elizabeth II delivery office on April 20, 2016 in Windsor, Britain. The visit marks the 500th Anniversary of the Royal Mail delivery service. The Queen and Duke of Edinburgh are carrying out engagements in Windsor ahead of the Queen's 90th Birthday tommorow. REUTERS/Chris Jackson/Pool

WINDSOR, ENGLAND - APRIL 20: Queen Elizabeth II shares a joke with postmen about their shorts as she visits the Queen Elizabeth II delivery office on April 20, 2016 in Windsor, Britain. The visit marks the 500th Anniversary of the Royal Mail delivery service. The Queen and Duke of Edinburgh are carrying out engagements in Windsor ahead of the Queen's 90th Birthday tommorow. REUTERS/Chris Jackson/Pool

Queen Elizabeth II shares a joke with postmen about their shorts as she visits the Queen Elizabeth II delivery office in Windsor with Prince Philip, Duke of Edinburgh on April 20, 2016 in Windsor, Britain. The visit marks the 500th Anniversary of the Royal Mail delivery service. The Queen and Duke of Edinburgh are carrying out engagements in Windsor ahead of the Queen's 90th Birthday tommorow. REUTERS/Chris Jackson/Pool

Queen Elizabeth II meets postmen as she visits the Queen Elizabeth II delivery office in Windsor with Prince Philip, Duke of Edinburgh on April 20, 2016 in Windsor, Britain. The visit marks the 500th Anniversary of the Royal Mail delivery service. The Queen and Duke of Edinburgh are carrying out engagements in Windsor ahead of the Queen's 90th Birthday tommorow. REUTERS/Chris Jackson/Pool

A postman of Japan Post rides a motorcycle in Tokyo, February 18, 2015. Financial giant Japan Post Holdings Co Ltd launched its global expansion strategy with its largest ever deal on Wednesday, agreeing a A$6.5 billion ($5.1 billion) takeover of Australian freight and logistics firm Toll Holdings Ltd. REUTERS/Issei Kato (JAPAN - Tags: BUSINESS)

Postman Fiete Nissen, 64, poses in his trolley on the track from the coast of Dagebuell, some 180 kilometers north of Hamburg, to the tiny North Sea islands of Oland and Langeness on his last working-day, September 30, 2014. Nissen was the official postman for the islands' 139 residents for more than 37 years.
REUTERS/Fabian Bimmer (GERMANY - Tags: SOCIETY)

A postal worker adjusts his neck gaiter against the wind in Minneapolis, January 27, 2014. Bitter cold and high winds surging down from the Arctic pushed wind chills to dangerous lows across the U.S. upper Midwest on Monday, forcing officials to close schools and warn drivers off roads, and slowing public transit and river traffic. REUTERS/Eric Miller (UNITED STATES - Tags: ENVIRONMENT)

A UPS delivery man struggles to push a cart through Columbus Circle as snow falls in New York January 21, 2014. A fast-moving winter storm forecast to dump as much as a foot of snow on the northeastern United States on Tuesday was expected to disrupt the evening commute for millions of people along the densely populated coast. REUTERS/Gary Hershorn (UNITED STATES - Tags: ENVIRONMENT)

A Canada Post employee delivers mail in Ottawa December 11, 2013. Canada's postal service will phase out urban home delivery within five years and hike the cost of postage stamps to try to stem soaring losses, the post office said on Wednesday. REUTERS/Chris Wattie (CANADA - Tags: BUSINESS EMPLOYMENT)

A postman delivers a letter to Yesenia Cruz Rodriguez (unseen), 41, while she waits for the judicial commission to carry out her eviction in Madrid October 7, 2013. Cruz's brother, Carlos Roberto Quinones Rodriguez, stopped making his mortgage payments two years ago, when he became unemployed. He returned to his native El Salvador in search for work while his sister Yesenia, who is currently out of a job, stayed on at the house in Madrid. Even though Cruz Rodriguez's eviction was later postponed until October 31, she followed up with a trip to her Bankia bank branch with her sister and anti-eviction activists to negotiate an agreement of dation in payment. The bank refused the offer of property capitulation in exchange for cancelling the debt, and instead offered Cruz Rodriguez the choice to rent one of its apartments at social housing rates. REUTERS/Susana Vera (SPAIN - Tags: SOCIETY BUSINESS REAL ESTATE POLITICS)

A postman takes a break in the Andalusian capital of Seville, southern Spain September 24, 2013. Spain's economy has expanded between 0.1 percent and 0.2 percent from July to end-September compared to the prior quarter, Prime Minister Mariano Rajoy said in an interview published on the Wallk Street Journal web site on Monday. REUTERS/Marcelo del Pozo (SPAIN - Tags: SOCIETY BUSINESS)

Royal Mail postman Donnie Macdonald delivers mail in Glen Tilt, Highland Perthshire, in Scotland July 24, 2013. After three aborted privatisation attempts in 19 years, Britain's Royal Mail postal service looks closer than ever to a sale that would end almost five centuries of ties to the state. Photograph taken on July 24, 2013. REUTERS/Russell Cheyne (BRITAIN - Tags: BUSINESS POLITICS)

Royal Mail postman Donnie Macdonald delivers mail in Highland Perthshire, Scotland July 26, 2013. REUTERS/Russell Cheyne (BRITAIN - Tags: BUSINESS EMPLOYMENT)

Royal Mail postman Donnie Macdonald sorts mail at a sorting office in Highland Perthshire, Scotland July 26, 2013. REUTERS/Russell Cheyne (BRITAIN - Tags: BUSINESS EMPLOYMENT)

Ronald Ruff of Hungary rides his bicycle as he makes a delivery run for bicycle courier company Eadessopedala (And Now Pedal) in Rome June 27, 2013. Ruff, 37, moved from his country with his wife and 4 sons to help company founder Tomas-Laszlo Simon in the business. Eadessopedala, which was founded in 2008 by Hungarian businessman Tomas-Laszlo Simon, currently has an annual turnover of about 100,000 euros ($130, 300) and employs 12 Italians. According to an April 2 poll from the Milan Chamber of Commerce, small businesses led by foreigners employ some 70,000 people in Italy. Picture taken June 27, 2013. REUTERS/Max Rossi (ITALY - Tags: BUSINESS EMPLOYMENT SOCIETY SPORT CYCLING TPX IMAGES OF THE DAY)

Manuel Albanese of Italy returns to the premises of bicycle courier company Eadessopedala (And Now Pedal) after a delivery run in Rome, June 27, 2013. Albanese, 28, has a master's degree in political science and earns a monthly salary of 350 euros ($458) which he supplements with 200 euros ($330) he makes as a waiter over the weekends. He lives and splits rent with three friends. Eadessopedala, which was founded in 2008 by Hungarian businessman Tomas-Laszlo Simon, currently has an annual turnover of about 100,000 euros ($130, 300) and employs 12 Italians. According to an April 2 poll from the Milan Chamber of Commerce, small businesses led by foreigners employ some 70,000 people in Italy. Picture taken June 27, 2013. REUTERS/Max Rossi (ITALY - Tags: BUSINESS EMPLOYMENT SOCIETY SPORT CYCLING)

U.S. postal workers load their trucks with mail for delivery from their postal station in Carlsbad, California February 6, 2013. The Postal Service plans to drop Saturday delivery of first-class mail by August in its latest effort to cut costs after losing nearly $16 billion last fiscal year, the cash-strapped mail agency said on Wednesday.
REUTERS/Mike Blake (UNITED STATES - Tags: BUSINESS EMPLOYMENT POLITICS)

A mailman walks by homes devastated by fires during Superstorm Sandy in the Belle Harbor section of the Queens borough of New York November 15, 2012. REUTERS/Shannon Stapleton (UNITED STATES - Tags: ENVIRONMENT DISASTER)

A postman carries a doll representing a shark during a protest in front of the Portuguese parliament in Lisbon October 9, 2012. Postmen protested against the privatization of the Post Office. REUTERS/Rafael Marchante (PORTUGAL - Tags: BUSINESS POLITICS CIVIL UNREST TPX IMAGES OF THE DAY EMPLOYMENT)

A worker loads packages onto a bicycle as he prepares to deliver them in central Beijing, December 22, 2011. In China's fragmented but booming express delivery industry, delay, damage and outright loss of packages persistently erode Chinese operators' reliability and reputations. This should be a huge business opportunity for foreign companies such as FedEx Corp and United Parcel Service Inc, which have vast experience in delivering packages around the planet, but they are sparsely represented in China. Foreign firms can deliver packages from abroad to destinations in China, but Chinese law forbids them from domestic delivery, packages sent between locations in China. This year, however, some are hoping to take a bigger bite out of this expanding pie, applying for licenses for parcel delivery in the Chinese market. Picture taken December 22, 2011. To match CHINA/EXPRESS-DELIVERY REUTERS/Staff (CHINA - Tags: SOCIETY BUSINESS)

Postnl employee Jaap Bouwmans delivers mail on his bicycle in his hometown Veghel May 20, 2011. With the split of PostNL from the international express arm of its Dutch parent group TNT legally finalised on May 31, 2011, many think Chief Executive Harry Koorstra is faced with the impossible challenge of rescuing the postal business from terminal decline, requiring ever deeper cost cuts and lay-offs. REUTERS/ Jerry Lampen (NETHERLANDS - Tags: BUSINESS SOCIETY)

A messenger sits in front of the headquarters of KB (Komercni Banka) bank in central Prague April 1, 2011. REUTERS/David W Cerny (CZECH REPUBLIC - Tags: BUSINESS)

Postman Gerhard Beck wades through the flooded streets as he delivers letters and postcards in the old part of Wertheim, 100km south of Frankfurt, January 17, 2011. The old part of Wertheim is completely flooded by rivers Tauber and Main. REUTERS/Kai Pfaffenbach (GERMANY - Tags: DISASTER ENVIRONMENT)

United Parcel Service worker Ryan Hewitt looks for an address as he pulls a sled to make deliveries through snowy conditions in Minneapolis, December 22, 2010. Today is the busiest delivery day of the year for UPS. REUTERS/Eric Miller (UNITED STATES - Tags: BUSINESS ENVIRONMENT IMAGES OF THE DAY)

Postal workers return to a delivery office in west London September 10, 2010. The British government said on Friday it planned legislation this year to privatise state-owned postal delivery company Royal Mail, despite opposition from trades unions. REUTERS/Toby Melville (BRITAIN - Tags: EMPLOYMENT BUSINESS TRANSPORT)

A postman distributes letters at the home of France's richest woman, Liliane Bettencourt, in Neuilly-sur-Seine, near Paris July 26, 2010. The wealth manager of France's richest woman has denied giving illegal cash donations to Labour Minister Eric Woerth, ahead of the questioning of the L'Oreal heiress and the minister by police later this week. The allegation was made by a former bookkeeper for Liliane Bettencourt, 87, main shareholder in cosmetics giant L'Oreal , and has led to probes into alleged tax evasion and money laundering, transfixing France and embarrassing President Nicolas Sarkozy's government. REUTERS/Benoit Tessier (FRANCE - Tags: POLITICS BUSINESS CRIME LAW)

Postmen dress as Santa Claus ride on their delivery motorbikes during an event to begin their Christmas season service at the Central Post Office in Seoul December 21, 2009. REUTERS/Choi Bu-Seok (SOUTH KOREA - Tags: SOCIETY EMPLOYMENT BUSINESS)

FedEx Ground driver John Amihero delivers packages in Washington September 17, 2009. Today FedEx Corporation reported a 53 percent drop in quarterly profit as the worldwide economic downturn continued to weigh on shipping volumes. The package delivery giant and economic bellweather said most of its markets were continuing to show signs of improvement. REUTERS/Yuri Gripas (UNITED STATES BUSINESS)

FedEx ground driver John Amihero delivers packages in Washington September 17, 2009. FedEx Corp reported a 53 percent drop in quarterly profit on Thursday as the worldwide economic downturn continued to weigh on shipping volumes. The package delivery giant and economic bellweather said most of its markets were continuing to show signs of improvement. REUTERS/Yuri Gripas (UNITED STATES BUSINESS)

An Australia post worker walks past an investment advertising in central Sydney September 1, 2009. Reserve Bank of Australia will announce its latest interest rate decision on Tuesday. REUTERS/Daniel Munoz (AUSTRALIA BUSINESS)

An employee of German postal service Deutsche Post AG rides a bicycle through the streets in Berlin January 16, 2008. REUTERS/Tobias Schwarz (GERMANY)

An employee of German postal service Deutsche Post AG leaves a distribution office in Berlin January 16, 2008. REUTERS/Tobias Schwarz (GERMANY)

An Argentinian post office worker seals the doors of a truck after it was loaded with ballot boxes which will be used for the upcoming presidential election, in Buenos Aires October 26, 2007. Argentineans will go to the polls in the first round of voting for their next president on October 28. REUTERS/Ivan Alvarado (CHILE)

An employee of German postal service Deutsche Post AG blows into a whistle during a demonstration of some 30,000 people against the Europe cross market liberalisation of the postal service at Berlin's Potsdamer Platz May 14, 2007. REUTERS/Wolfgang Rattay (GERMANY)

South Korean postmen in Santa Claus outfits wave before leaving to deliver gifts to needy neighbourhoods during a charity campaign for the upcoming Christmas holiday season in Seoul December 23, 2005. REUTERS/Kim Kyung-Hoon