I'm a bit late it sharing this news, so I apologize for that. I don't often promote or endorse a product unless I know it strictly complies to a gut-healthy diet, and the quality is good.
Primal Kitchen mayonnaise has long been a favourite of mine. It is the only mayo on the market that I know of that is 100% grain free (using a non-grain derived vinegar), and it uses only avocado oil (a healthy fat). Additionally it is sugar free, soy and canola free and dairy free.