The result of a strike ballot among 8,000 postal workers is expected to be revealed this afternoon.
The ballot of Communications Workers Union members was called as part of a pay dispute and union officials have already said they expect a sizeable majority to back the strike plans.
An Post has offered the CWU a gradual 9.5% pay increase, as well as 15% of the company as part of a profit-sharing scheme.
However, the union said these are merely allowances and will not be pensionable or reckonable for sick pay and holiday pay.