Building an address list that is worth something
A large list without engagement is worth less than a small attentive one. That sounds obvious, and yet almost everybody optimises the wrong number.
Ask for little
An email address, and a first name if you genuinely personalise. Every extra field costs sign-ups without improving quality.
Say what you will send
The subject and the frequency, before sign-up. People who know what to expect unsubscribe considerably less and report spam less often.
Use confirmed opt-in
A sign-up confirmed by a click in a verification message removes typos and malicious entries. You lose a little volume and gain a lot of deliverability.
Never buy a list
It is not only against the rules: those addresses contain spam traps that damage your reputation for a long time. One send can cost you months.
Clean regularly
Remove people who have opened nothing in a year, after one reactivation attempt. A shorter list performs better.