i find my immersion blender to come in handy for several tasks like making smoothies and blending soup in the pot. and while it can make mayonnaise, i find that whisking by hand yields such better results, and it's not that hard to do. part of the problem with the immersion blender is that the blades don't reach far down enough, and it's hard to get the emulsificaiton started. also, it's easy to inadvertently overblend the mayo so that it gets too stiff. whisking by hand is totally worth the few extra minutes' effort. just be meticulous about adding the oil in a drop at a time initially until the mayo starts to bind.

I disagree with pierino. best mayo I've ever made was with my immersion blender. If you have the cup it came with, that's the perfect vessel to make mayo in.

You can make mayonnaise with a hand whisk if you have enough stamina, so a good immersion blender should work just fine, just add the oil very slowly.

Yes, badly. Immersion blenders are one of the most useless tools I've come across.

Yes! I just made Amanda's milk mayonnaise with an immersion blender. I would suggest that you blend it in a container that is narrow enough to let the bottom of the immersion blend to be immersed. If it is too shallow, the blades won't reach the liquid. Also the container should be high enough so that the splatters won't get everywhere.

http://www.food52.com/recipes/3041_milk_mayonnaise_maionese_de_leite