Is it permissible to talk and laugh with female cousins in front of everyone, and is it permissible to shake hands with an uncle's wife?

It is permissible for a man to speak with a woman out of necessity if there is no fear of temptation, such as enjoining good and forbidding evil, or for education, buying, and selling. However, this must be without joking or softening of speech, without seclusion, and without casting a prohibited gaze, while the woman adheres to the legal hijab. It is permissible to greet elderly women, but it is disliked for young men and women to initiate or return greetings due to the temptation involved. It is forbidden for a non-mahram man to laugh and joke with a young woman due to the temptation and softening of speech involved. Some scholars have explicitly stated that a non-mahram woman laughing with a non-mahram man is forbidden and warrants disciplinary action. Everyone must adhere to the manners of Islam, including hijab, not softening of speech, and lowering the gaze. Allah has forbidden seclusion with a non-mahram woman, prohibited her from softening her speech, commanded lowering the gaze, and for addressing a woman from behind a screen. Shaking hands with a non-mahram woman is forbidden, except for an elderly woman who is not desired, and an old man if there is no fear of temptation. The relatives of a woman's husband are considered non-mahrams, and it is particularly emphasized that they are prevented from entering upon her or touching her.