Preview generators
Email inbox preview generator
Preview how your sender name, subject line, and preheader render in the Gmail app on a phone, where truncation is tightest, with best-practice checks.
Instructions
How to use this tool
- 01Enter your sender name, subject line, and preview text (preheader).
- 02Watch where the Gmail app cuts your subject, at roughly 35 characters, and your preview text, at roughly 45.
- 03Review the checks: subject length, preheader usage, and common spam-filter tripwires.
- 04Download the PNG to share the inbox rendering in reviews.
Background
The three lines that decide your open rate
Before anyone sees your beautiful email body, they see exactly three strings in a list: sender name, subject, and preview text. The sender name earns the most trust (people open people they recognize), the subject earns the click, and the preheader is a free second subject line that most senders waste on View this email in your browser.
Display budgets differ by client and device, and the phone is the one that matters: the Gmail app cuts the subject at roughly 35 characters where Gmail on a desktop allows about 70. This preview shows the phone, because a subject that survives there survives everywhere. Front-load the payoff so truncation cannot hide it.
Background
What the checks look for
The subject checks flag lengths outside the 20 to 50 character sweet spot, all-caps subjects, fake Re: and Fwd: prefixes, and stacked exclamation marks, all of which correlate with spam-folder placement and eroded trust. The preheader check verifies you are actually using the space: an empty preheader means clients pull the first text they find in the body, which is rarely what you would choose.
These are heuristics, not a deliverability score. Inbox placement depends primarily on authentication (SPF, DKIM, DMARC) and sender reputation, which the deliverability tools in this hub cover.
FAQ
Frequently asked questions
How long should an email subject line be?
20 to 50 characters is the reliable range: long enough to say something specific, short enough to survive mobile truncation, which lands around 35 characters in the Gmail app. The essential words belong at the front.
What is a preheader?
The snippet of text email clients show after the subject in the list view, pulled from a hidden preheader element or the first text in your body. Treat it as a second subject line that completes the first rather than repeating it.
Do emoji in subject lines help or hurt?
Measured effects are mixed and audience-dependent: an emoji can lift visibility in a plain inbox but reads as promotional in others, and some clients render them inconsistently. Test with your own list rather than assuming.
Does this tool test spam filtering or deliverability?
No. It previews rendering and flags copy-level red flags. Actual inbox placement is governed by SPF, DKIM, DMARC, and sender reputation; use the DMARC, SPF, and DKIM checkers in this hub for that layer.
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