Deliveries to an east London estate have been suspended after a gang attacked a postman on his rounds.
About 1,800 addresses on the Brownfield estate in Poplar will not receive mail from Saturday and it is not known when services will resume.
A 44-year-old man was treated for head injuries after being punched, kicked and beaten with a belt on 24 March.
It followed reports of intimidation on the estate. Postmen went out in pairs in the days after the attack.
Scotland Yard said a postman was surrounded by about 20 youths after emptying a post box outside Balfron Towers at 1000 GMT.
They stole some letters, punched, kicked and beat him with a belt buckle before throwing a manhole cover at him.
The postman, who has two children, was left traumatised but has since left hospital. He lived near the estate but the family has now moved out.
Royal Mail says it is difficult to say how long the suspension of deliveries will last.
Dave Joyce, health and safety officer for the Communication Workers' Union (CWU) said: "Our local officials are concerned...that no arrests have been made following what was a very serious assault that could easily have resulted in a murder."
He said the CWU had received reports of an increase in assaults and threats against postmen and women in the area.
"We will be pressing the police to become more visibly active in investigating the crime and tracking down and bringing to justice the thugs who carried out this attack."
A Scotland Yard spokesman said the case was being investigated from the Limehouse station and asked any witnesses to call police.
One teenager who kept attacking the postman after the others stopped was described as about 17, Asian, with short, light brown hair and wore a light waist-length jacket.