The posties have been balloted following action in Fife in support of Dave Mitchell, a postal worker with 27 years service who was sacked from his job after a number of “test” items, such as greetings card with vouchers and cash inside, went missing.
Mr Mitchell, 57, from Chance Inn in Fife, who lost his job in December 2014, has maintained his innocence and took his case to an employment tribunal.
Tribunal judge Ian McFatridge twice ordered his reinstatement, saying there were no reasonable ground for the belief Mr Mitchell had stolen mail, but Royal Mail refused to comply.
Former colleagues in Cupar have held two 24-hour strikes - one a week before Christmas last year and the second in January 2016.
Customers, friends and family have held ‘silent’ protests outside the Cupar delivery office and the case has the backing of North East Fife SNP MP Stephen Gethins.
Kenny Logan, Scotland branch secretary of the Communications Workers Union, said he believed strike action looked likely in the EH, (Edinburgh and Lothians), TD (Borders), FK (Stirling and central area) and KY (Glenrothes and Fife) postcodes.
“I firmly believe we’ll get a massive “Yes” vote from our members. This should get Royal Mail to look again at their decision on sacking Dave Mitchell.
“Strike action will be on the cards if Royal Mail do not adhere to the two points we’ve made to them over this case.
“Firstly, we want to see Mr Mitchell reinstated, and secondly, we want to see an independent review which would be legally binding.”
Mr Mitchell said: “The main thing is that this could happen to any postie throughout the country.
“If they feel they’ve been unfairly dismissed they could do what I did, go to a tribunal and win it, and not get their job back. I’m keeping my fingers crossed the ballot will go my way.
“But I will not give up. I’ve done absolutely nothing wrong. Twenty-seven years of service with the Royal Mail and this is what I get. I just want justice.”
Mr Mitchell previously described the moment he was apprehended as being “like something out of The Sweeney”.
A Royal Mail spokeswoman said: “Royal Mail is disappointed that the CWU (the Communications Union) is balloting its members across four postcodes in the east of Scotland for industrial action over an employment tribunal case.
“We are continuing to talk to our people and unions about this matter.
“A ballot for industrial action does not mean that any action will take place.”