The inbox row is the first thing you ship
Before anyone sees your email design, they see three pieces of text in a crowded inbox: the sender name, the subject line, and the preheader. Those three decide the open. This tool renders them as an inbox row so you can judge the combination the way a subscriber will — at a glance, partially truncated, next to forty other emails.
Type the sender name, subject, and preheader and the preview, character counts, and truncation checks update live.
How much text actually shows
Every client truncates differently, but the working budgets are:
- Subject line: mobile clients commonly show around 30–40 characters; desktop clients show more, often 60–70. Write so the first ~35 characters carry the message.
- Preheader: anywhere from ~40 to ~100 characters depending on client and screen. It’s bonus space — use it to extend the subject, not repeat it.
- Sender name: around 20–25 characters before truncation in many mobile clients. A recognisable name beats a clever one; people open senders they trust.
Writing subject lines that survive truncation
- Front-load the point. “Your March report is ready — plus 3 fixes” survives cutting; “We’ve got something special we think you’ll really like:” doesn’t.
- Make subject and preheader a pair: subject states the value, preheader adds specificity or urgency. Avoid the default trap of the preheader showing “View this email in your browser.”
- Be specific over cute. Curiosity-gap subjects can win opens but erode trust when the payoff disappoints — and opens aren’t the goal, clicks and conversions are.
- Sentence case generally reads more natural than Title Case, and ALL CAPS plus heavy punctuation (!!!, $$$) pattern-matches to spam for both filters and humans.
Frequently asked questions
What is a preheader and where do I set it?
The preheader (or preview text) is the snippet shown after the subject line in the inbox list. Email platforms expose it as a dedicated field; technically it’s the first text the client finds in the email body. If you don’t set it, subscribers see whatever happens to be first — often a logo’s alt text or an unsubscribe link.
Do emoji in subject lines help or hurt?
They can lift visibility in a text-only inbox, but rendering varies across clients, some audiences read them as unprofessional, and overuse is a spam signal. If you use one, make it reinforce the message, put it where truncation won’t strand it, and A/B test against the plain version rather than assuming.
Does this tool predict spam filtering or open rates?
No — it previews length, truncation, and inbox appearance. Deliverability depends mostly on sender reputation, authentication (SPF, DKIM, DMARC), and list quality, not magic words. The honest way to compare subject lines is a split test; size it with the sample size calculator.
Should the sender be a person or the brand?
Test it with your audience. A common strong pattern is “Person at Brand” (“Maya at campaign.name”) — personal enough to feel human, branded enough to be recognised. Whatever you choose, keep it consistent; the sender name is how subscribers learn to spot you.