Smelly Washing Machine vs the Open Door Policy

With most of the front load washers, there's a lot of recommendations that you have to keep the front door open to enable the inside washing drum to air dry out. I have to say that for the first few years that owned my washer that I did NOT do that. I think that after year 3 of owning my washer that I started to have an odor problem with mold in the machine. I've been through about 3-4 different types of liquid detergents and I haven't been able to pinpoint which one is causing or caused the problem.

Currently, we're using powdered detergent. Additionally, we're also leaving the front washer door open so that the washer airs out. For about 3 weeks, we had NO odor coming from the washer. Note: this is after the fact that I ran the machine through a battery of cleaning techniques to get rid of the mold and odor. I went back to liquid detergent to finish it out after our test batch of powder detergent was used up. My odors did come back even with the door left open. Now while the odor wasn't as bad as it was before. It did come back. With that in mind, we have definitely switched back to powdered soap. The detergent we were using was a Costco liquid HE detergent but I can't remember which one it was. I'll have to say that I have to see whether the odor comes back after a few weeks with powdered or not to rule out a timeline possibility with odor but I highly suspect that it is the case that the detergent causes the build up.