What's the least painful way to get mildew smell out of clothes?

rewash on the hottest the label allows with a cup of white vinegar in the drum and half the usual detergent, then dry them outside if you can. sunlight does a lot. if the smell survives that, soak overnight in oxygen bleach and wash again. in an older place it might be the washer though. run it empty on a hot cycle, wipe out the door seal and the drawer, and leave the door open between washes. and never leave a wet load sitting in it.