Postal workers in Belfast are not collecting or delivering mail today as a show of respect to a murdered Catholic postman.
Members of the Communications Workers Union will also not make any deliveries tomorrow in memory of Daniel McColgan.
Mr McColgan was shot dead as he arrived for work at a sorting office yesterday morning in the loyalist Rathcoole estate.
Security forces are on high alert in the wake of the murder and unions say the situation will be reassessed tomorrow.
Some workers believe they should not return to normal working until after the man's funeral next week.
Mr John Keggie, the union's deputy general secretary, says there is a feeling of "shock and anger" among postal workers across the country.
The Police Service of Northern Ireland are also investigating simultaneous gun attacks on two houses in the Co Armagh towns of Lurgan and Portadown. No one was injured in either attack.
Police say Mr McColgan had been picked out for murder for no other reason than that he was a Catholic in a loyalist area.
The so-called Red Hand Defenders - a cover name used in the past by both the Ulster Defence Association and the Loyalist Volunteer Force - claimed responsibility.
They say they now consider all Catholic postal workers to be "legitimate targets". Security sources say they believe the UDA is responsible.
PA