So I was in a class and we were putting together an email. The writer started double spacing after a period, and I pointed out that that was not necessary, as we no longer use typewriters, so single space is now standard. This other guy in class told me I was wrong, and in fact double spacing is proper.
Later, in the same email, the writer wrote a sentence with the word "and" in the middle, and I felt like a comma would be appropriate. The same other person responded that a comma was not necessary before "and", and then went on to say I really don't know anything about writing. We'll ignore the cheekiness, as well as the single space rule. But are there circumstance where "and" does not have to be preceded by a comma? I feel like maybe you have already addressed this.