Definition
Subject line best practices are the guidelines that research and testing have proven to improve open rates. They include recommendations for length, tone, personalisation, urgency, and format. The subject line is the first thing subscribers see and the primary factor in whether they open the email.
Key Best Practices
- Keep it under 60 characters: This ensures the subject line is fully visible on most desktop clients. Mobile truncation typically occurs around 78 characters.
- Front-load important words: Put the key benefit or hook in the first 30-40 characters where it is most visible.
- Personalise when appropriate: Using a subscriber's name or location can increase open rates, but overuse reduces impact.
- Create genuine urgency or curiosity: Subject lines that hint at time-limited offers or interesting content perform well, but false urgency damages trust.
- Avoid spam trigger words: ALL CAPS, excessive punctuation, and words like "free," "act now," and "guaranteed" can trigger spam filters.
- Test consistently: A/B test subject lines regularly to understand what resonates with your specific audience.
Related Glossary Terms
A/B Testing
A/B testing in email marketing is the practice of sending two variations of an email to a small sample of your list to determine which version performs better before sending the winner to the remaining subscribers.
Abandoned Cart Email
An abandoned cart email is an automated message sent to customers who added items to their online shopping cart but left without completing the purchase. It is one of the highest-converting email types in ecommerce.
AIDA Model for Email
The AIDA model (Attention, Interest, Desire, Action) is a classic copywriting framework used to structure email campaigns that guide subscribers from awareness to conversion.
AMP for Email
AMP for Email is a Google-developed framework that allows email messages to include interactive elements like forms, carousels, accordions, and live content. It turns static emails into dynamic, interactive experiences directly inside the inbox.
Anchoring Effect in Email Marketing
The anchoring effect is a cognitive bias where the first piece of information presented (the anchor) influences subsequent decisions, used in email to frame pricing and value perception.
Announcement Email
An announcement email is a dedicated campaign that communicates a specific update, milestone, or change to subscribers, from product launches and feature releases to company news and events.