The mailboxes are part of the common areas. As a condo owner, you are only responsible for what you can see in your apt. However, you are asking about replacement, not repair. That would be a board or managing agent decision on whether replacement is in order. They would have to replace them all uniformly.
Halstead Property, LLC
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The management is responsible for all common area elements. That's why owners pay common charges.
Global Market Specialist
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