Personalization is only as effective as the data that powers it—and when that data is wrong, it’s downright irritating.

Email remains an extremely reliable and popular way for brands to communicate with their audience, with an enviable return on investment. Though there are few signs of adoption waning, many marketers are working to head off future problems of relevancy by embracing sophisticated data practices and emerging technologies.

Lauren Henderson, marketing manager at Minibar Delivery, explains the significance of effectively scheduling marketing emails.

Sandro Roco, director of strategic initiatives for subscription clothing delivery service Bombfell, discusses the role customer input plays in personalization.

Less than half of brands include a "buy now" button of some sort in their email campaigns, missing a chance to convert shoppers who may have left items in a cart without completing a purchase.

Email appears to be the medium of choice for messaging with retailers among UK internet users who communicate regularly with brands.

Internet users of all ages in Germany are surprisingly similar in the ways they interact with retailers via email.

Marketers think great content and a good reputation make for effective mailings. Consumers see it differently.

Email is a dependable method of marketing communication in many markets, including Indonesia. More than three in 10 email users there reported that getting promotions from retailers was one of the main reasons they checked their email.

Retailers haven't cracked the code on email marketing. The volume of mail they send keeps rising, but KPIs are not following suit.

Email marketing open rates in the UK were high in 2016, but clickthrough rates fell—possibly due to the absence of engaging content.

Jessamyn Block, director of marketing at smart jewelry company Ringly, explains how email marketing helps the brand retain customers.

Amanda Tolleson, CMO at Birchbox, shares how the company uses email marketing to connect the digital and physical aspects of its business.

Postmates’ Tanner McGrath and Appboy’s Bill Magnuson discuss how real-time data insights help improve broad marketing campaigns both immediately and in the long term.

Alex Weinstein, director of marketing technology and CRM at eBay, spoke with eMarketer about how the company built its own personalization platform.

Finding the right message depends on the business goal

Email marketing—a marketing mainstay—only works when it is not abused. Research shows that US internet users are most likely to unsubscribe from email lists because they get too many emails.

Rajiv Doshi, director of digital marketing at pickled vegetable company Mezzetta, discusses how the brand is pushing past vanity metrics to more effectively measure the success of its influencer marketing campaigns.

Other message types may be buzzier, but one-size-fits-all email newsletters continue to be the backbone of marketers' email efforts. There's a good reason for that: They work.