In large mixing bowl, sift dry ingredients .Cream in mayo gradually.
Add coffee slowly while beating.
Add vanilla last.
Place in a greased 9 x 13 pan.
Bake at 350 for 20 minutes.
Turn the temperature down to 325 for the rest of the time, usually 5-10 more minutes.
Toothpick inserted in the center should come out clean. Add frosting of your choice when the cake is cool.