Postal workers in Merseyside are taking unofficial strike action for a fourth day, despite a possible agreement to end the national dispute.
The Liverpool action is in a dispute over shift patterns
At a meeting at Aintree Racecourse on Friday, 800 Merseyside staff voted to reject proposals to return to work.
Mark Walsh, from the Communication Workers Union (CWU), said: "The result is a resounding no vote."
Meanwhile, a deal to end the national dispute is being put to the union's executive on Monday.
Mr Walsh said: "It is something I have to say, in 20 years of being involved in the trade union I have never seen anything like it in my life.
"There was not a hand from any man or woman in the room to return to work. I hope it does not come to legal action."
The wildcat walkout, prompted by a row over shift patterns, began on Wednesday after the end of the official strike.
The CWU has claimed Royal Mail in Liverpool has refused to renegotiate on shift times.
Nationally, the union and the Royal Mail struck a deal late on Friday night and sources said they believed the deal will be accepted.
The Royal Mail obtained a High Court injunction on Friday to prevent strikes going ahead on Monday and Tuesday.