What is the ruling on shaking hands with a non-mahram woman, and what if that happened by mistake due to crowds?

Shaking hands with a non-mahram woman is forbidden and an evil act. Whoever intentionally does so must repent to Allah, seek His forgiveness, and not return to it. As for one who does so by mistake, unintentionally, and immediately withdraws, there is no sin upon him, for the Prophet, peace and blessings be upon him, said: "Indeed, Allah has pardoned for my Ummah their mistakes, their forgetfulness, and what they are coerced into."