Here's the ingredient list[1] for their "mayo". Seems vegan to me. Looks like they offer varieties with and without preservatives. I didn't dig any further to see what else they put in the one with preservatives.
Ingredients: Non-GMO Expeller Pressed Canola Oil, Filtered Water, Lemon Juice, White Vinegar, 2% or less of the following: Organic Sugar, Salt, Pea Protein, Spices, Modified Food Starch, Beta-Carotene. Just Mayo is also available with preservative.