There is a widespread custom among the Jewish people to fill up their kiddush cup to the point that it overflows. This overflowing of wine symbolizes Hashems blessing overflowing in our lives. I was told by someone that this wine is compared to the wine that we spill out during Pesach for the ten makkos which al pi kaballah is a high level of klippah and shouldnt even be touched let alone drunk.
Question: What if any is the source that one should not drink the wine that spills out of the kiddush cup as described above.