While many marketers use brackets at the beginning of email subject lines, new data from subjectline.com shows placing them at the end is boosting open rates. This tactic works by drawing the reader's eye to a key callout, and contrary to myth, it does not negatively impact deliverability or land emails in spam.

Contrary to recent best practices, testing shows that starting a newsletter subject line with the edition number (e.g., "[Scoop #42]") can now significantly increase open rates. This highlights the need to constantly re-test old marketing tactics as user behavior evolves.

Contrary to old advice, adding a newsletter edition number to the subject line is now highly effective. Specifically, putting the edition in brackets (e.g., "[Scoop #12]") before the main subject line has been shown in A/B tests to increase open rates by approximately 20% compared to a standard subject line.

A highly effective email tactic is using a compelling statistic as the entire subject line, with no other text or call to action. This piques curiosity by presenting a data-driven statement, leading to an average open rate increase of 19%.

Visually disrupt a standard subject line by adding a period after every word, such as "This. Changes. Everything.". This unconventional formatting creates a subconscious sense of drama and forces a unique reading pace. This slight mental disruption grabs attention in a crowded inbox, leading to a significant increase in open rates.

A previously deprecated tactic, placing the newsletter edition number (e.g., "Scoop #42") at the start of the subject line is now significantly lifting open rates. This highlights the cyclical nature of marketing tactics and the need for continuous re-testing of so-called "bad" practices.

Contrary to old email marketing wisdom, testing fully capitalized subject lines can significantly increase open rates by 3-4 percentage points. Modern spam filters are less likely to penalize this tactic, making it a viable test for grabbing attention in a crowded inbox.

A counterintuitive yet effective email tactic is capitalizing an entire word in the middle of a subject line, not at the start or end. This simple, cost-free A/B test is trending because it breaks visual patterns in the inbox, leading to a reported 16% open rate increase for B2B and 21% for B2C.

To make an email stand out, use a subject line under three words and remove the preheader text. This creates visual white space around your message, distinguishing it from the 98% of emails that use preheaders. This visual disruption can skyrocket open rates.