Reference: I’laam al-Mu’aasireen bi-Fataawa Ibn ‘Uthaymeen – Page 384
Question: Is it permissible to shake the hand of a woman if doing so is from the custom of the people of the land?
Response: We say this is not permissible, even if you find the custom of the people is to shake the hand of a woman; Therefore, it is obligatory to abandon this custom.