The commissioner of Canada Elections says the NDP broke no rules when several MPs sent taxpayer-funded mailings to households in 2013 during or close to a series of federal byelections that year.

In a letter to NDP national director Anne McGrath, Yves Cote says he's exonerating the party after investigating several complaints about large-volume mailings from MP offices in four federal ridings: Bourassa in Montreal, Brandon-Souris and Provencher in Manitoba and Toronto Centre.

"I have reached the conclusion that no offence under the Act was committed with respect to these various mailings," he wrote.

Cote's findings are based on documentation provided by the NDP and they vary according to the riding he examined.

He found that in Provencher, all the mailings were sent outside the writ period, and therefore did not fall within the Elections Canada definition of election advertising.

In the case of Bourassa and Toronto Centre, Cote found that some of the mailings went out on Oct. 18, two days before the writs dropped. The party demonstrated that it subsequently and unsuccessfully tried to recall the mailings once they learned the byelections had been officially called. Elections Canada rules state that any mailing that's in transit when the writ is dropped and which cannot be recalled, will not be deemed an election expense.

Cote also found that while NDP mailings in both Bourassa and Brandon Souris did go out during the writ period, the NDP "properly" reported them as a byelections expense to Elections Canada.

'We've always followed the rules'

NDP Leader Tom Mulcair, on a pre-election tour of Ontario, welcomed the findings.

"We've said all along that we've always followed the rules, we knew that we had followed the rules," he said. "But I am glad to see on the eve of this federal election, that we've been cleared by Elections Canada from the false allegations put forward by our adversaries."

Cote also said he did not pursue two other areas of complaint.

One was NDP MPs' inclusion of links to party web sites in their parliamentary mailings that the complainant deemed partisan in nature. Cote says partisan use of a parliamentary resource is "not sufficient cause for the resource to be regulated by the (Canada Elections) Act." And he also pointed to a decision by Elections Canada in 2000 that it would "no longer engage in a review of mailed material to determine whether it 'directly promotes the MP and thus constitutes an election expense.'"

Cote added that the production and printing costs of the mailings were paid by the NDP and so he did not review the content of the mailings.

The original complaint was filed by Liberal MP Marc Garneau in March, 2014 and referred to the mass mailings sent to voters about the Bourassa byelection. The riding was won by Liberal candidate Emmanuel Dubourg by a 48 per cent margin.