How long should an email subject line be?

Aim for about 41 characters or fewer. That is roughly where many mobile email clients stop showing the subject and truncate it, and over half of email is opened on mobile. The tool shows each line's length and highlights those at 41 characters or under in green.

What words trigger spam filters?

Aggressive sales language such as free, guarantee, act now, risk-free, 100%, and rows of dollar signs raise a message's spam score, especially in combination. The tool flags these words inline so you can rephrase. Modern filters weigh many signals, but avoiding obvious triggers still helps deliverability.

What are the four subject-line angles?

Curiosity opens a loop the reader wants closed. Urgency uses a deadline to prompt action. Personalization uses the recipient's name or context. Benefit states the clear value of opening. Different lists respond to different angles, so test across them rather than always using one.

Should I personalize every subject line?

Personalization can lift open rates, but only when it feels relevant rather than gimmicky. Using a first name works best when the rest of the email is genuinely tailored. If you only have a name and nothing else personal, a strong benefit or curiosity line often performs just as well.

Does the tool send my campaign data anywhere?

No. Subject lines are generated in your browser from your inputs. Your topic, recipient name, and email type are never uploaded, so you can draft campaign ideas privately.

Email Subject Line Generator

The subject line decides whether your email gets opened or ignored. This generator produces variations across the four angles that drive opens — curiosity, urgency, personalization, and benefit — and checks each one for length and spam triggers so you ship lines that actually land in the inbox.

How it works

Your topic, optional first name, and email type fill proven subject formulas. Each angle pulls a different lever:

curiosity        →  The one thing about your spring sale nobody tells you
urgency          →  Last chance: our spring sale
personalization  →  {first_name}, this is for you
benefit          →  A simpler way to handle your spring sale

Two checks run on every line. The character count is compared against the ~41-character mobile truncation point (lines at or under that are highlighted), and the text is scanned for common spam-trigger words like “free”, “guarantee”, and “act now”, which are flagged inline.

Tips and notes

Selecting the transactional type reshapes the lines to be plain and specific (“Your order is ready”, “Please confirm your booking”) because receipts and confirmations should never look like marketing. Leave the name field blank to keep the {first_name} merge token so you can paste straight into your email platform. Test a few angles against the same list rather than guessing — open rates vary a lot by audience, and the only reliable answer is your own data.