“Everybody has them”, the mail lady said when I told her we got rid of ours, for good, it would seem. Here’s how we deterred them: We sprayed disinfectant around the opening of the mailbox and into it after removing both wasps and the nest they were starting to build.
Now, anything that destroys the chemical “scent” for the wasps will do the job. Try what you have in the house – pine cleaner, essential oils, cleaning alcohol… Try it out and share your experiences 