The New Democratic Party dipped into Canada's election voters list to send Christmas cards from party leader Jagmeet Singh to dozens of home addresses.

"That should never have happened," said NDP spokesman George Soule.

The party was alerted to the problem earlier this week after Christmas cards from Singh began to arrive at the home addresses of several people, including reporters and producers at the CBC. The NDP says it is still trying to find out how many addresses were obtained from the voters list.

Journalists routinely receive Christmas cards from politicians of all political stripes. Usually, they're sent to their office addresses.

This year's seasonal greeting card from the office of Jagmeet Singh, showing the NDP leader with his wife Gurkiran Kaur Sidhu. (CBC News)

Soule said the party has since destroyed the Christmas card list that contained information from the voters list and has notified the Office of the Commissioner of Canada Elections of the breach. The commissioner's office investigates and prosecutes violations of Canada's federal elections law.

Under the Elections Act, it is considered a criminal offence for a political party to use information in the list of electors in an unauthorized manner. The law provides for fines of up to $10,000 and/or imprisonment for up to one year.

Under Canada's Elections Act, registered political parties are provided with copies of the List of Electors, which includes the names and addresses of everyone eligible to vote in Canada.

Registered parties are authorized to use the list, particularly during elections, "to communicate with electors, including for the purposes of soliciting contributions and recruiting party members."

They are, however, prohibited from using the information on that list for any other purpose — and Elections Canada recommends that parties keep the list under lock and key.

Myriam Croussette, spokeswoman for the Commissioner of Canada Elections office, said using the list to send Christmas cards could count as "communicating with electors" under the law.

"Sending holiday greeting cards is a manner of communicating with electors," she said. "In fact, it is a common practice for parties to distribute such material."

"The list of electors should be kept in a secure and restricted area when not in use, such as a locked filing cabinet. The electronic copy of the lists of electors should be stored on a secure, password-protected computer," say the Elections Canada guidelines. "Passwords and keys to the area where lists of electors are stored should be strictly controlled by the person responsible for safeguards."

Elections Canada also recommends that parties destroy their copies of the lists after an election, or when a revised list is issued.

Soule said the problem began when staff in Singh's office started to put together the mailing list for holiday cards and noticed that some of the names didn't have addresses. A junior staff member called someone they knew at the party office with access to the party's database, and that person supplied the missing addresses.

"We are reviewing the processes for mailings to ensure that this does not happen again," Soule said.

Privacy advocates have raised concerns in the past about federal political parties' use of the data they receive from Elections Canada to build databases of information about voters. While federal political parties are not subject to Canada's privacy laws, they are subject to the Elections Act.

Privacy Commissioner Daniel Therrien has recommended that federal political parties be required to obey federal privacy laws.

Elizabeth Thompson can be reached at elizabeth.thompson@cbc.ca