Cork Mail Centre is to close - with 240 people to lose their jobs.
An Post's facility in Little Island will completely shut in nine months' time.
An Post met staff last night to let them know the Cork Mail Centre will close on a phased basis between September and next March.
An Post says the 11 million euro annual savings from the plant closure will enable An Post to invest more parcels infrastructure.
But 161 part-time and 79 full-time staff are to lose their jobs in Cork Mails Centre over the next nine months - with some being redeployed.
The Communications Workers' Union says it's extremely disappointed with the decision, saying it's devastating news for staff.
The Union says the decision will be devastating to those affected and that it will have detailed negotiations with An Post to ensure that those losing their jobs will be supported.