Members of the Communications Workers Union said that as a mark of respect to their colleague murdered by loyalists this morning they will not collect any mail tomorrow nor make deliveries on Monday.
The situation will be reassessed and some workers believe they should not return to normal working until after the man's funeral next week.
The decision was made at a meeting in Belfast and the union will be contacting its Northern Ireland members to talk about safety in the wake of the murder.
Mr Billy Hayes, general secretary of the Communication Workers' Union, said tonight he understood the reaction of postal workers in Northern Ireland wanting to make a gesture in support of their murdered colleague.
"This was an outrageous sectarian attack but it only strengthens our resolve to support the peace process.
"Postal workers, as with other public servants, work at the forefront of problems in the community."
Mr John Keggie, the union's deputy general secretary, said there was a feeling of "shock and anger" among postal workers across the country.
"The perpetrators of this attack should hang their heads in shame because this was a young postman doing his best to serve his local community. It has caused deep shock," he said.
The Red Hand Defenders said today they now consider all Catholic postal workers to be "legitimate targets".
PA