Mother's Day email subject lines that elicit emotion have a 21.5% higher open rate than those that do not, according to recent research from Yesmail and Persado.

The report was based on an analysis of 118,000 emails sent by Yesmail clients during the two weeks leading up to Mother's Day in 2014 and 2015. More than 12,000 unique subject lines were included in the data set.

Nearly two-thirds of all Mother's Day-themed emails include subject lines the elicit at least one emotion, the analysis found.

The average open rate for these emails is 10.3%, compared with 8.5% for those that do not elicit an emotion.

The most effective emotions to elicit in Mother's Day email subject lines are encouragement and curiosity; the least effective is safety.

Campaigns incorporating Mother's Day references at the beginning of their subject lines are significantly more effective, the analysis found. These subject lines generate an open rate of 11.2%, on average, compared with 9.7% for emails that contain a Mother's Day reference at the end of their subject lines.

That trend is particularly noticeable on mobile devices. Mobile open rates for Mother's Day emails increase 37% if the Mother's Day reference is at the beginning of the subject line.

About the research: The report was based on an analysis of 118,000 emails sent by Yesmail clients during the two weeks leading up to Mother's Day in 2014 and 2015. More than 12,000 unique subject lines were included in the dataset.