MailChimp debuts testing feature
It then automatically determines the subject line with the highest conversion rate and the better subject line is sent to the remainder of the subscriber's list.
The feature lets subscribers choose the percentage of e-mails they want to send to each campaign on their mailing list. For example, a subscriber can send an e-mail with the subject line “Save Now” to 10% of their list and the same e-mail with the subject line “Free Shipping” to another 10%. MailChimp then sends the campaign to 20% of the list.
The feature then monitors the open and click-through rates and, after 24 hours, sends out the remaining 80% of the list using the subject line that has the best rates.