Should an AC condensation line run directly into a sewer line?

If ur condensation line is drain thru ur sewer line...The code required to have a p-trap set up. The reason is lethal gas is produced in ur sewer line (Methane gas) and it go where ever ur line is til it's escape thru the toilet vent on top of the roof. The funny smell could be just mildew smell from ur basement. This correction must done by a qualify plumber because it's a liability issue. Lawsuit is scary and we as techncians must follow all city codes to even giving advices as to the closes form.