Is it permissible to mix with Muslims who amass their wealth from both lawful and unlawful sources (such as trading in alcohol and pork), and to eat their food when invited, and is it permissible to accept their donations to the mosque from this money?

Those who deal in forbidden things must be advised and warned against the dire consequences of earning unlawful money, and reminded of Allah's punishment. If they respond, repent, and redress grievances, then it is permissible to associate with them, eat their food, and accept their donations for charitable causes, as Allah Almighty says: "So whoever receives an admonition from his Lord and desists, he will have what is past, and his affair is entrusted to Allah." But if they persist in forbidden acts after being advised, then they must be boycotted and their donations refused as a deterrent to them.