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