The new site, Minameddelanden.se ('Mymessages.se'), is managed by the Swedish Tax Authority (Skatteverket) and enables Swedish public authorities to "mediate electronic messages" to individuals and companies.
The new "digital mailbox" is expected to save the state millions of kronor, according to the Dagens Nyheter (DN) newspaper.
Government agencies in Sweden already provide a number of services online, including applying for social insurance benefits and filing tax returns.
But the new "supersite" will bring together all correspondence from different public agencies at both the national and local level into one online location.
Opting into the service is voluntary, however, and currently only the tax agency, the Swedish Transport Agency (Transportstyrelsen), and the Swedish Companies Registration Office (Bolagsverket) are included.
But more agencies are expected to join the service in the future.
"There's a desire for a collective service where you can find everything in terms of contacts with the state," Lena Warstrand, a spokeswoman for E-delegationen, Sweden's e-government taskforce, told DN.
The group is currently looking at how much the state spends on postage, but is also exploring a wider range of online services that would allow Swedes to exercise power of attorney for banking and other matters.
According to DN, Swedish government agencies spent 995 million kronor ($155 million) in postage in 2009.
Another concept under discussion is a "digital folder" that would allow Swedes to store digital copies of receipts and other important documents to make it easier to find them.
The tax agency plans to launch a public awareness campaign about the site later in the year, despite concerns by elderly Swedes that they will be left behind.
"Not all Swedes have access to the internet," Curt Persson, head of the Swedish Pensioners Association (Pensionärernas riksförbund, PRO) told DN.
"We don't to have digital exclusion."