An Post is planning to cut a further 1,600 jobs between now and 2015.
The job cuts will be secured through voluntary redundancy, non replacement of staff and a reduction in overtime.
The semi-state company has already shed 730 jobs over the past two years.
An Post says the ongoing effects of the recession have impacted right across its business with traditional mail volumes down 7% last year.
It said that the jobs cuts are necessary to offset the impact of the ongoing recession, falling mail volumes and increased competition.