Preview text isn't optional for email newsletters
Most people skip the preview text field
Your newsletter tool probably has a field labeled "preview text" or "preheader" somewhere near the subject line. Most people leave it blank. Then the email client pulls the first chunk of body copy — usually "View this email in your browser" or the first sentence of your opening paragraph.
That's the text that shows up in the inbox list view, right next to your subject line. It's often longer than the subject line itself. And you're letting the system decide what goes there.
It's a second subject line
The subject line gets people to notice. The preview text gets them to open. They work together. A good subject line with auto-generated preview text is like writing half a headline.
Your subject line might be "Three quick fixes for slow image loads." Your preview text could be "Each one takes under five minutes and doesn't require a CDN." Now someone scanning their inbox knows what the email contains and whether it's relevant right now.
Or your subject line is "New post: Image dimensions belong in your content model" and your preview text is "View this email in your browser." One of these setups respects the reader's time.
Write it after the subject line, before the body
Preview text should extend the subject line, not repeat it. The reader has already seen the subject. They're deciding whether to open. Give them one more concrete reason.
If your subject line asks a question, the preview text can hint at the answer. If your subject line makes a claim, the preview text can add specificity. If your subject line is a topic, the preview text is the angle.
Keep it under 100 characters. Some clients cut it off at 50. Front-load the useful part.
It shows up in search and forwards too
When someone searches their inbox for your newsletter, preview text appears in those results. When they forward your email, the preview text is part of what the next person sees before opening.
This isn't about open-rate optimization tricks. It's about making your email readable in the format people actually use to decide what to read. The inbox list view is your email's context. Preview text works like alt text for people who won't see the image — it describes what's inside for someone who hasn't opened it yet.
Set a content model rule for it
If you send regular newsletters, make preview text a required field in your production checklist. Write it at the same time you write the subject line. If you're using a template, put the preview text field at the top of the form, right under the subject line field, so you can't skip it by accident.
Don't let your email tool auto-generate the most visible piece of text in your reader's inbox. That's your job.