I have a list of clients. But the list is a mixed list, I mean there plenty of new clients along with plenty of old clients. So, I can't just email them what I am doing or selling right now. What should I do?
Offer something they both will want. Obviously in your industry there must have been something that is universal.
Before offering them something. Build a relationship first. See how they are reacting to your emails.
Once you have known their behavior then send emails according to their need.