Is homemade mayonnaise safe?

Yes it is. It is recommended that you use pasteurized eggs to make homemade mayonnaise. Keep it refigerated.

How is mayonnaise made?

Mayonnaise is traditionally made by emulsifying a combination of raw egg yolks with oil, and then mixing in some sort of acidic ingredient, usually vinegar or lemon juice

How to fix homemade mayo that doesn't emulsify

It can be fixed. Grab a fresh egg yolk, and slowly beat your broken mayonnaise into the yolk . The fresh yolk will help to re-emulsify the sauce, bringing everything together and making for a smooth and happy sauce.