hole behind 3 overflow holes?

I'm installing a Porcher bathroom sink. The sink has 3 overflow holes, and directly behind these holes ia single hole on the underside of the sink. If the sink fills up & water goes through the overflow holes, it leaks out of the hole behind the overflow holes. Should there be some kind of hose that goes from this hole to the drain or should I just seal the hole somehow? Please help!

drain

We would have to know more about the sink, such as a model number that we can reference something about it. Usually, from your description, there is are two fittings with hose between them. One goes at the overflow and the other on the bottom of the sink and the drain goes through it.

Hole behind 3 overflow holes

Model #: 1002.12.006 It's a black basin with gold leaf around the inside. I believe it's called "Turning Leaves". Made by Porcher - Arroyo Self Rim. Made in U.S.A. - 10/17/2003. I also need to know if the overflow holes go to the front or back of the basin. Thanks for any help.

hole behind overflow holes

Found out....according to Porcher, the hole is to relieve pressure during production. Should have been plugged before shipping, but was not. Trying to get a plug from Porcher. If that doesn't happen, does anyone know if fiberglass patch will work on vitreous china sink?

I would say they owe you a new sink!