More than 95% of staff who voted in the ballot wanted to strike action, according to the Communication Workers Union CWU, which represents more than 110,000 postal workers at the Royal Mail.
Royal Mail has offered a pay deal that is worth up to 9% over 18 months, but the CWU wants more given the rate at which prices are rising.
They said more customers could be switched to competitors because of the threat of more strike action by CWU members.
We want the CWU to consider our best and final pay offer and work with us to secure its future. They said that was in the best interests of Royal Mail and all of its employees.
He said that for Royal Mail to function normally again, there needs to be a change in the negotiating approach from its leadership that recognizes the depth of feeling from the workforce that make their company.
Some 115,000 workers planned to walk out on February 16 in order to 17 February in an ongoing row over pay and conditions.
Hundreds of thousands of workers - including teachers, civil servants and barristers - have recently been on strike over pay, which they say should keep pace with rising prices.