Email Preheader Text: How It Affects Opens and Deliverability
Learn how email preheader text affects open rates and deliverability. Best practices for writing preheaders that complement your subject line and improve engagement.
The preheader is the text that appears next to or below your subject line in the inbox. It's the second line of your email's first impression. A good preheader increases opens. A bad preheader — or no preheader at all — wastes valuable inbox real estate.
While preheader text doesn't directly trigger spam filters, it affects engagement, and engagement affects deliverability.
What Is Preheader Text?
The preheader (also called preview text) is extracted from your email's content and displayed in the inbox alongside the subject line:
| Element | Where It Shows | Character Limit |
|---|---|---|
| Subject line | Primary — bold text in inbox | 40–50 characters visible on mobile |
| Preheader | Secondary — lighter text after subject | 40–130 characters depending on client |
If you don't set a preheader, email clients pull the first text from your email body. This often results in showing things like "View in browser" or "Having trouble viewing this email?" — wasted space that tells the recipient nothing useful.
How Preheaders Affect Deliverability
The Engagement Connection
Preheaders influence whether someone opens your email. Higher open rates lead to better sender reputation, which leads to better inbox placement:
- Good preheader → more opens → higher engagement rate
- Higher engagement → better sender reputation
- Better reputation → better inbox placement
The effect is indirect but real. Every improvement to your open rate compounds into better deliverability over time.
What Not to Do
Preheaders that mislead or confuse can generate complaints:
- Don't promise something the email doesn't deliver
- Don't use deceptive urgency ("Your account will be deleted")
- Don't stuff keywords — this can look spammy to both recipients and filters
Focus on what matters most
Preheaders help with engagement, but authentication drives deliverability. Check your SPF, DKIM, and DMARC first.
Best Practices
Complement, Don't Repeat
The preheader should add information, not echo the subject line:
| Subject Line | Bad Preheader | Good Preheader |
|---|---|---|
| New features this month | Check out our new features | Dashboard redesign, bulk export, and API v3 |
| Your order has shipped | Your order shipped today | Arrives Wednesday. Track your package. |
| 50% off this weekend | 50% off sale this weekend only | Code WEEKEND50 — ends Sunday at midnight |
Keep It Concise
Most email clients show 40–90 characters of preheader text. Front-load the most important information:
- Put the key message in the first 40 characters
- Additional context in characters 40–90
- Anything beyond 90 characters is rarely displayed
Set It Explicitly
Don't let email clients auto-generate your preheader from body content. Set it explicitly in your email's HTML using hidden preheader text. Most ESPs have a dedicated preheader field in their email editors.
Test Across Clients
Preheader display varies significantly:
| Client | Preheader Behavior |
|---|---|
| Gmail (web) | Shows subject + preheader on same line |
| Gmail (mobile) | Shows preheader below subject |
| Apple Mail | Shows 1–2 lines of preview text |
| Outlook | Shows limited preheader, varies by version |
A/B Test Preheaders
Test different preheader approaches:
- Specific details vs curiosity-driven teasers
- With emoji vs without
- Short (30 characters) vs long (80+ characters)
- Question format vs statement format
Track open rates to determine what works for your audience.
Common Preheader Mistakes
Not Setting One at All
The default preheader is usually the first text in your email: "View this email in your browser" or navigation links. This tells the recipient nothing about why they should open.
Too Long
Extremely long preheaders can display awkwardly in some email clients, showing partial sentences that trail off.
Mismatched Tone
If your subject line is serious ("Important account update") but your preheader is casual ("Hey, just wanted to let you know..."), the mismatch can feel off.
Using Preheader as a Second Subject Line
The preheader works best as a complement — additional context, a specific detail, or a call to action. Making it a second subject line wastes the opportunity to provide new information.