5 email testing ideas

1. Opt-in incentives - Providing a tangible incentive for new opt-ins such as a coupon or free gift.
   Dell offered 20% off select products resulting in 14x lift in average opt-in rate during the holiday season.
2. Personalisation - The closer you can get to creating a sense of one-to-one communication, the better the response is likely to be. Expedia sent emails from a real travel consultant i.e."Cathy Cruiser" resulting in 5.5% higher opens, 23% higher CTR and less unsubscribs and spam flags. Personalising the subject line with the recipient’s first name e.g. "Dave, Your 7 Day Alaskan Cruise Awaits.", resulted in 10% lift in opens.
3. Call-to-action (CTA) placement and button size - Increasing the size, shape or color of buttons and the placement of CTA, can often increase clicks. Salesforce.com moved the CTA from a small box on right side to just below the message’s headline and made buttons larger resulting in 26% increased in CTR.
4. Video links - Watching online video is one of the most popular activities on the Internet. Promote video content in your messages by displaying a screenshot of the video and embedding a link for video playback. Interactive Intelligence, included video screenshots and playback links in their email newsletters resulting in double or triple the number of clicks as text links.
5. Email frequency - Testing the point at which you maximize revenue from messages without increasing the rate of unsubscribes. An ecommerce company who sell special-occasion gifts identified a highly motivated and loyal segment and tested various message frequencies, ranging from one message every other day to one message every three weeks. Sending an email once every other day increased revenue 3x compared to sending email once a week. Unsubscribe rates on a per-message basis did not rise significantly. 

Example email creative