Canada Post and the union representing most of its employees are turning up the pressure on each other and the public, as their negotiators grind away with little sign of movement at the table after nearly a week of rotating strikes.

There will be 13 communities hit by 24-hour strikes on Thursday -- the most since walkouts began last week -- and the postal service is preparing to reduce mail deliveries to three times a week starting Monday.

Canada Post will also cut staffing levels at its mail sorting plants and pay unionized letter carriers only for the three days they work, Canada Post spokesman Jon Hamilton said in an interview Wednesday.

"This is all as a result of the 50 per cent drop we've seen in our volumes in the last five days due to the union's rotating strike activity," Hamilton said.

"We can't keep our costs the same while we've seen our business drop by half. We need to take action now to avoid significant losses that would harm our financial self-sustainability."

Union national president Denis Lemelin said Canada Post's announcement wasn't all that surprising and wouldn't change the union's negotiating strategy.

"That's what they expect for next week, but (it's) only Wednesday," Lemelin said. "We'll see what happens tomorrow at the table."

Lemelin said the union told the federal mediator Wednesday evening that it wanted to meet with Canada Post and present a response to the company's latest proposals.

He said CUPW chose 13 smaller locals for Thursday's strike "because we want to address the issue of jobs in the community and expansion of services to the community in smaller places in the country."

The communities are: Labrador City, N.L., Acadie-Bathurst, N.B., Summerside, P.E.I., Ste-Therese and Ste-Jerome, Que.; the Ontario cities of Thunder Bay, Hearst, Brantford and St. Thomas, Flin Flon, Man., Vernon, B.C., and the territorial capitals of Yellowknife, N.W.T. and Whitehorse, Yukon.

Canada Post's spokesman said the strikes have had a disastrous effect on customer confidence.

"While the union has had rotating strikes in certain communities, their activity has caused Canadians from coast to coast to lose confidence -- hopefully temporarily -- in our ability to deliver and therefore are putting a lot less mail into the system," Hamilton said.

One of the companies that has been affected by the strike is Birds & Beans, an organic coffee seller that has seen its online orders plunge and its administrative headaches grow because of the upheaval at Canada Post.

"Our volume is down because people aren't even coming to our site because they think they're not going to get their stuff shipped," Madeleine Pritchard, who owns the Toronto-based business with husband David.

Pritchard said their business has switched to couriers because of the uncertainty but their systems aren't electronically integrated for such things as shipping notices and tracking.

She noted that entering information the old-fashioned way is adding "more time and errors" and increasing expenses by several hundred dollars per week.

"I could stand the several hundred dollars a week if it weren't for all of the other pain," Pritchard said.

The president of a CUPW local in Edmonton -- one of two cities where strikes were held Wednesday -- said that mail volumes in their plant hasn't dropped by as much as the company says.

"People are saying, actually, that there's still mail being moved and we haven't seen the reductions that Canada Post is claiming as a result of the strikes," Bev Ray said from Edmonton. "We have not seen a 50 per cent drop."

Ray did say that fewer parcels were being shipped and those that were being sent were being diverted to courier service Purolator, in which Canada Post owns a major stake.

Hamilton said Canada Post stands by its numbers and repeated the company's position.

"We have up-to-date counts on the amount of mail and parcels and all that in the system. But all you would have to do is walk through any of our facilities and you could see quite clearly that we are dealing with a lot less mail than we normally do," Hamilton said from Ottawa.

He also repeated the company's position that the strikes aren't necessary because union and Canada Post negotiators continue to talk -- although there hasn't been much progress and many issues.

"The union keeps saying they're having rotating strikes because the want to get the company to the table. We're at the table," Hamilton said.

"But we're not at the table to discuss adding a billion dollars of labour costs over the next four years, we're not at the table to discuss stopping any efforts under way to modernize this company and secure our future. That's not what we're there to talk about. We're there to talk about generous terms and conditions for the next four years that will make our employees better off than they are today."

Canada Post has said its latest offer includes annual wage increases that for current employees would bring the top wage rate to $26 an hour, job security, no changes to a defined benefit pension plan, medical benefits and "generous" vacation leave that tops out at seven weeks per year.

Future hires would get a starting wage of $19 an hour, rising to a maximum $26 an hour, up to six weeks vacation and a defined benefit pension by age 60.

Rotating strikes began last Friday in Winnipeg and have since been held in Hamilton, Montreal, Moncton, N.B., Victoria, Calgary and Edmonton.