An email has to clear three separate hurdles: arriving in the inbox, being opened, and being read. Each is a different problem, and failing any one of them makes the others irrelevant.
The subject line decides whether anything else happens. What works:
Do not waste the preview text
The preview text — the line the inbox shows after the subject — is the second most-read thing and the most commonly wasted. Left alone it often shows "View this email in your browser". Setting it deliberately gives you a second line to earn the open.
| Metric | What it indicates |
|---|---|
| Delivery rate | Whether the email arrived at all — a list quality signal |
| Open rate | Whether the subject line worked (approximate, see below) |
| Click rate | Whether the content persuaded anyone to act |
| Unsubscribe rate | Whether you are sending what people expected |
| Spam complaints | A serious warning — investigate immediately |
Open rates have become unreliable. Privacy features in several major email clients pre-load tracking images, which registers as an open whether or not anyone read anything. Treat open rate as a rough directional signal, and rely on click rate as the more honest measure of whether an email worked.
A welcome sequence — a few emails sent automatically after someone subscribes — is the highest-value automation available, because new subscribers are at their most interested immediately after signing up.
A simple version: an immediate email delivering whatever was promised, then one introducing what you do, then one pointing at your most useful existing content. Written once, it works for every future subscriber without further effort.