Email Subject Line Preview
Email Subject Line Preview — see how your subject line looks in Gmail and Apple Mail before sending. Check length, spam words, and emoji. Free, no signup.
About Email Subject Line Preview
The Email Subject Line Preview shows you exactly how your subject line will appear in Gmail and Apple Mail before you send — including how it truncates on mobile, where emojis land, and whether any words flag spam filters. Write better email subjects with real inbox previews, not guesswork.
The subject line is the most important line in any email campaign. Every other element — the copy, the design, the offer — is irrelevant if the recipient does not open the email in the first place. Open rates for commercial emails typically range from 15-30% depending on the industry, which means that on most campaigns, the majority of recipients make a pass/fail decision based solely on the subject line visible in their inbox. Optimizing that single line of text is one of the highest-leverage actions in email marketing.
The challenge is that subject lines render differently across email clients and devices. Gmail desktop shows around 60-70 characters. Gmail mobile, which accounts for a large portion of email opens, shows only 30-40 characters before truncating. Apple Mail shows slightly more. A perfectly crafted 80-character subject that reads beautifully on desktop looks like a broken sentence on mobile — and that truncation point is invisible until you see the actual inbox preview.
The tool solves this by rendering a realistic inbox preview for each major client. You see exactly where your subject line gets cut off, which words or punctuation marks fall after the truncation point, and how the emoji renders (or fails to render) in each client’s font. This lets you adjust the word order to ensure the most important part of your message appears before the cutoff on every device.
Spam word detection flags common trigger phrases that email providers use to identify promotional or junk email. Even one flagged phrase can increase the likelihood of your email landing in the spam folder rather than the inbox, regardless of how carefully crafted the rest of the email is. Seeing the warning before you send lets you choose alternative phrasing.
Free, no signup required, available in any browser.
Frequently asked questions
Aim for 30-50 characters for the best open rates across all devices. Subjects over 70 characters will be cut off on most mobile email clients, which account for more than half of all email opens.
Emojis can boost open rates by 10-25% when used sparingly and relevantly. Avoid overusing them — one emoji that matches your content works better than several random ones.
Avoid words like FREE, WINNER, URGENT, ACT NOW, CLICK NOW, and GUARANTEED. These are common spam triggers that can send your email to the junk folder before it is ever seen.
The tool shows inbox previews for Gmail desktop, Gmail mobile, and Apple Mail — the three most widely used email clients globally, covering the majority of your recipients.