Airbnb as reception venue?

Since you will only have 6 people, and they are also staying at the Airbnb I wouldn't worry about it. It would be one thing if you were trying to host 20+ people, but since its 6, I honestly wouldn't even say anything to the host. I know they say no events, but if the event is only occurring with all the house guests I don't see how it could be an issue.

Many rentals don't allow events to be held at the house. You'll need to check the details on each rental that seems to fit your needs. You might even contact the owners and explain that it will be only six people. I'm sure they would be far more agreeable to that size of event than one that was a party for 50 or 100. With only 6 people, I would hope they wouldn't charge extra for cleaning, but you never know. If they do, that should be part of a written agreement.

You will need to be clear with the host about the event and see if they are comfortable with it. I caution against Airbnb venues though. My husband and I had originally planned to do an Airbnb wedding, but three months prior to our wedding the property owners sold the place and we were left with no venue. Thankfully we were able to figure something else out, but I wouldn't wish that stress on anyone.