The rotating strikes at Canada Post ended Tuesday and the service is still trying to clear a backlog of parcels, but it seems they may face more potential delays.
There have been at least two protests that blocked trucks from travelling in and out of mail facilities, including Wednesday night in Stoney Creek.
Hamilton Police were called.
They say they spoke to the protestors but that demonstration was peaceful and no arrests were made.
It does not appear the demonstrators were union members.
One was carrying a sign that included a URL for the website of a communist student group which supports the union.
Canada Post responded with a tweet that read, "We can confirm individuals are illegally obstructing the movement of mail/parcels at our Hamilton Mail Processing Plant, 393 Millen Rd, Stoney Creek, Ontario. We'll continue to take appropriate action to address illegal activity impacting the collection & delivery of mail/parcels"