On what grounds?
It is “inserting religion into the workplace.”
Oh, and since when is that illegal, or inappropriate to the workplace? My faith is the source of the whole shape of my life; how can I help but “insert religion into the workplace”? It’s not like saying this phrase is proselytizing on company time; it’s simply that someone chose to be offended.
Not a good omen, considering that Canada Post is a Crown corporation.