The Portugese government decided Thursday to sell up to 70 percent of the national post service as part of the privatisation programme under its international bailout.
The sale will be made by an initial public offering on the national stock market and directly to a number of financial institutions which will be required to then sell the shares on the market, the government said in a statement.
The sale price is to be fixed later.
Five percent of the shares up for sale are to be reserved for employees at a discount.
The government statement did not specify when the IPO will take place, but officials have said they hope to conduct it by the end of the year.
Portugal promised to privatise the postal service, currently 100 percent owned by the state, under the 78-billion-euro ($106 billion) EU-IMF bailout the eurozone state concluded in May 2011.
The government will retain the remaining 30 percent stake.
The postal service is considered a more promising Portugese state asset, earning a net profit of 31.6 million euros in the first half of 2013.
The company, which employs over 13,000 people, is estimated to be worth 600 million euros, according to the Portugese media.