Canada Post is changing thousands of defective locks on new community mailboxes after it received complaints from residents across the country unable to access their mail last winter.

The Crown corporation's massive overhaul of locks is taking place across Quebec and also in other provinces such as Newfoundland, Ontario and Prince Edward Island, Radio-Canada has learned.

"We won't disclose the numbers, but we are changing the locks in areas where problems occurred last year," said Phil Legault, a spokesperson for Canada Post.

The initiative comes after residents complained of having to wait days and sometimes weeks before they could retrieve their mail because their community mailboxes were frozen shut.

Canada Post accepted blame last year, saying the lock design on new boxes is susceptible to freezing when the cold weather sets in.

About 50,000 locks needs to be changed in the region of Saguenay, according to information obtained by Radio-Canada.

Replacements already underway

With the winter season approaching, Canada Post has already begun the process in some areas like Rouyn-Noranda, where more than 7,000 locks have been changed.

Frustrated residents filed complaints with the corporation after not being able to access their mail for weeks.

Out of desperation, some letter carriers in Abitibi took a hammer to the mailboxes in order to open them.

The lock design on new boxes is susceptible to freezing when the cold weather sets in. (Radio-Canada)

Last week, residents on Montreal's South Shore received new keys to their community boxes where the locks are soon to be replaced, according to a letter from Canada Post.

"Over the next few weeks, we will replace the lock on your community mailbox," reads the letter.

The problem appears to be specific to the new community boxes installed since 2014.

The boxes's defective locks were made in the United States.

Locks on the older generation of boxes were built in Quebec and appear to be functional.