The worsening problem has been caused by a national mania for home improvement that has seen the spread of porches and glass doors with floor-level letter boxes.
Now the aggrieved postmen say they will no longer stand, or rather, crouch for it. So fed up are they of injuries caused by the hazardous movement of bending down to ground level while carrying heavy mail bags that the Irish Republic's Communications Workers' Union is now threatening a boycott of impossibly low letter boxes.
Chris Hudson, a CWU official, himself an ex-postman, said: "It's not a laughing matter. I can remember the problems with my back and the sheer difficulty of bending down, getting mail into a letter-box which was at the bottom of a door, while trying to retain the bag on your back."
Branch officials have told some postal workers to deliver mail to site offices only on new estates where builders had told the union to "get lost".
The union wants parity with European counterparts. In the Netherlands the authorities have set a minimum height for letter boxes and the CWU is pressing the Department of the Environment to legislate for this in building regulations.
A 1992 survey by the Irish Business and Employers Confederation (IBEC) of 7,600 work injuries leading to claims against management found that 13 per cent involved back strain. A 1987-89 study of reportable accidents at work showed between 22 and 27 per cent annually involved back injuries.
Mr Hudson said members were not introducing an immediate ban, but locally the union and the postal service have urged builders to set letter boxes at hip height. "We don't seem to be getting much sympathy. Some builders and local authorities seem to think it's a joke."
He added that if local authorities failed to accept their responsibilities "it will get to the situation where we are compelled by our members to take some action".