Do short subject lines always perform better?

Myth: False. Subject line length does not determine performance. What matters is relevance, clarity, and compelling content. Short can be punchy; long can be descriptive. Both can work.

Mobile display may truncate long subjects, so front loading key information helps. But this is about user experience, not deliverability filtering.

Test what works for your audience. Some respond to brief subjects; others prefer detailed. Optimize based on data, not arbitrary length rules.