Postal workers in Bristol are holding a third day of official strike action on Tuesday following an unresolved dispute about overtime.
Communication Workers' Union (CWU) members took action on 15 and 26 August after contractual overtime was cut at Easton's Royal Mail depot.
Managers have been brought in to cover during the walk-out.
The Royal Mail said it could not justify the normal scheduled overtime as there was less post over the summer.
The CWU has proposed for the matter to be dealt with through their national headquarters.
The union warned the strike could cause severe disruption to deliveries and collections in the Easton, Fishponds and Lawrence Hill areas of the city.