It came after Mr Dey spoke with Communication Workers Union (CWU) representatives in the Scottish Parliament, where they updated politicians on their continuing dispute with the Royal Mail Group.
MSPs heard from the CWU about plans to cut 10,000 jobs, dismantle pay and conditions and end the universal service obligation.
The 48-hour strike went ahead on Thursday, November 24 and Friday, November 25 (Black Friday).
Mr Dey said: “Having met earlier this week with representatives of the CWU, whose members remain engaged in a protracted dispute with the Royal Mail Group, I wanted to make crystal clear my support for our posties.
“That’s why I visited the picket line outside the Dundee East Sorting Office, from which both Monifieth and Carnoustie are served.
“This is much more than a dispute about pay – it’s also about the conditions postal staff work under and, frankly, the very mail service we all receive.
"This is a workforce which has shown itself to be flexible and committed to serving the public. These staff do not deserve the treatment they are receiving from Royal Mail, whose actions also give rise to significant concern over the future of mail deliveries across the UK.”
“I was pleased to be able to communicate my support directly to our posties, and I’d encourage the public to get behind them as well.”
Additional industrial action was scheduled for today Thursday as well as further dates this month: Friday, December 9; Sunday, December 11; Wednesday, December 14; Thursday, December 15; Friday, December 23 and Saturday, December 24.
Craig Anderson, Scottish Secretary of the CWU, urged more politicians to get behind the postal workers’ action and joing the picket lines.
He said: “We were very pleased with the response from MSPs who came along to meet us in Parliament.
"They expressed their support for our posties and the services they provide to communities right across Scotland.
“We would encourage all MSPs to join our members on picket lines as we call for fair pay for our posties.”