“The easy confidence with which I know another man's religion is folly teaches me to suspect that my own is also.” -Mark Twain

It is common for English speakers to end a sentence with a preposition in informal situations. In formal language, however, ending a sentence with a preposition is consider poor grammar. So, in an informal conversation, I might say, "Are you enjoying the weather we've been blessed with?" However, since the word "with" is a preposition, it is not appropriate to say the same in a business email. In that case, you want to use correct English grammar and say, "Are you enjoying the weather with which we've been blessed?" If you are unfamiliar with prepositions, use this link to learn more about them: https://www.boone.k12.ky.us/userfiles/562/Classes/2991/prepositions-0.pdf

I'm trying to think of a good example with which to answer your question.

The villagers had to conform with an economic policy with which they did not agree.