I wouldn't say dwarfed but the answer looks to be ... maybe?
5.8 million tons of junk mail each year in the US. Mass of CO2 to mass of paper looks to be 10.5x for new paper and 3x for recycled, so depending on whether junk mail is primarily recycled or new, that is somewhere between 17 and 60 megatons of CO2 / year.
Looks like iron & steel is 7.2%. Non-ferrous metals are listed at 0.7%, so gold is ~1/3 of the CO2 of non-ferrous metal production.
Paper ("and pulp") is 0.6%.
https://ourworldindata.org/emissions-by-sector