Some social welfare payments are impacted.
An Post says deliveries in some rural areas are being impacted by staffing shortages.
The company says a spike in Covid-related absences has placed a "temporary strain" on its resources.
It says the worst impact's being felt across its mails and parcels network, and at some Post Offices, with some having to temporarily shut.
It says social welfare benefit payments will be transferred to a neighbouring office for those affected.