We have always reminded our customers to respect their subscribers. Only by respecting someone, will you make an effort to listen to them, understand their interests and give them what they need.
Engaging recipients critical for delivery, written by Laura from Word To The Wise, states how ISPs are changing their blocking and filtering decisions based on the behavior of your subscribers towards your newsletter. In simple terms, if subscribers feel you are giving them what they need (i.e. respecting their needs and interests), the ISPs will give you a better rating, thus improving your email delivery.