At the end of my second paragraph above, I meant to say holes for vents or even entire cutouts in the end/ribbon joist won't matter "because it isn't" spanning an open area like a joist would. Some people don't even use an end joist on the sill but just put 2by fillers in between the floor joists and then cover it with the exterior sheeting. I have seen plenty of dryers in the basement that go up and out between the joists and through the end joist so I believe they blow enough to work. Mine elbows down into the joist cavity and out about 5 feet. Yearly, I run a stick through it to clean it out because stuff does ball up inside.
You can tell when you run the dryer forever and it doesn't dry the clothes. The lack of flow causes the dryer to get to hot and the thermal cutoff switch shuts off the heat. Luckily it has worked an no fires.
Everyone should check their vents. Also those flex hoses get laid behind a dryer and then the dryer gets pushed back and pinches them off so they can plug up with lint there. Have removed and cleaned those alot. Sears sells a periscope looking vent made of metal that I like.
Not cleaning the lint filter can cause lint to start collecting around the drum and then dry lint contacting the electrodes results in a fire.