Yes. For the smoothest mayonnaise, blend the other ingredients beofre adding the oil, and then add the oil slowly in small amounts. Otherwise the mayonnaise can separate and you get a layer of oil over top of it as well as pockets of oil in it.
One more thing - if some bratty British kid starts whining and complaining, and starts asking for "salad cream" and calling your mayonnaise "puke", just bash the little tosser with your elbow. It worked for Basil Fawlty.