Anyone who imagines that his sustenance depends on whether or not he shakes hands with some woman – that person is a kofer. No question about it. It is a mitzvah to work to support one’s family, etc. But your parnassa is determined by Hashem on Rosh HaShanah; it is not determined by whether or not you shake hands with an isha.
“There is a B’feirush Gemara against that.” Source, please?