Productive people use the titles for their email differently than unproductive people. There's two main tactics to use. One is to simply put everything you're really trying to communicate to the receiver in the subject. I do that frequently and gets a lot of success. If it's a short, simple message just stated all in the subject, that way, the person never has to open it, you're not wasting that person's time. After a while and people realize you're not going to waste their time they're more receptive to reading your email.
The other tactic is to write the headline in such a way the subject is to explain to someone the benefits as to why they should read your email. It's essentially copywriting. But if all you do is put Hi Jim Reed This doesn't give Jim a big incentive to take That time and if Jim is in a big hurry, it's so easy to put that into a box or a category or file for later and then later never comes. So that's my advice for the subjects. Give people a sense of what it's about and the benefit they're going to get if they open your email and read it or say everything you need right there in the title.