Canadian homes and businesses will start receiving mail again Tuesday now that legislation forcing 48,000 locked-out postal workers back to their jobs has become law, Canada Post says.

Post offices that were closed during the labour dispute will start to reopen Tuesday as well, while mailboxes will be unsealed starting Monday, the Crown corporation said.

The announcement came Sunday night, shortly after the government's back-to-work-bill received royal assent.

The bill imposing a labour contract on the Canadian Union of Postal Workers was passed by the House of Commons on Saturday and the Senate on Sunday.

Just when Canadians can expect mail service to be back to normal isn’t clear, Canada Post suggested in a news release.

“With unprocessed mail in the system and accumulated mail received from other countries that has not yet entered our system, it will take some time to stabilize our operations and to return to our normal delivery standards," the release said.

The postal workers were locked out June 14 after 12 days of rotating strikes. They’ll all be called back within the next 24 to 48 hours, Canada Post said.

Senators question witnesses

In a rare Sunday sitting, the Senate spent more than seven hours studying the back-to-work bill and questioning witnesses before voting 53-26 in favour.

Union president Denis Lemelin told senators the union would respect the legislation if it passed, although it raises difficulties for employees, who weren't consulted about the provisions.

"I'm happy to be working for Canada Post, but I want to be treated fairly for the work I do," postal worker Pierre Brisson of Montreal said after the bill was enacted.

The law imposes a four-year contract on the workers, specifies pay increases and leaves other disputed issues to binding arbitration.

The House of Commons gave the bill final reading Saturday night after a filibuster by the Opposition NDP.

Although the labour disruption might not have bothered Canadians relying on electronic mail, the government argued the economy would lose millions of dollars a week. Small business and organizations were hit hard, Conservative MPs said.

"That was always the intent of the bill — to restore the mail service, to make sure that the economy will be held intact,” Labour Minister Lisa Raitt said.

Individuals also looked forward to the return of postal service.

"I still remember how to write letters, and I do write letters and put stamps on them,” said Randolph Ianniruberto of Alliston, Ont., who uses Canada Post to pay his bills and for correspondence.

Bill described as 'sledgehammer'

In the Senate, Liberal James Cowan said Bill C-6 gutted the collective bargaining process and he accused Prime Minister Harper of using a "sledgehammer" approach to solving the dispute.

"His solution was clear: break the monopoly of the Canadian Union of Postal Workers."

The senator read a quotation from Harper from 1997, in which he stated that ending the monopoly in the postal service "will ensure that Canadians are never held hostage by another postal strike."

Canada Post CEO Deepak Chopra told senators the Crown corporation "wants to welcome back employees in a special manner" and begin "long-term healing."

Faced with the prospect of stiff fines for violating the back-to-work measures, CUPW vice-president George Floresco said the union would comply with the legislation. But Floresco insisted the union would "carry on the struggle for a just collective agreement and just working conditions."

"We'll deliver the mail, but this isn't the end of it," Floresco told CBC News from Ottawa. "We'll continue to work with our allies who have been out on the street with us and supporting true negotiations, and we're not going to let this die."