Online retailers are getting lazy, irresponsible, and are disregarding best practices when it comes to responsible email marketing, according to a new study from Return Path.

These dire findings were based on buying items from 45 online retailers, then monitoring their transactional and promotional message streams. These emails messages were then compared with messages received by registering for the same retailers' email programs without making a purchase.

Here's what happened:

•  31% of companies added customers to their email lists following a purchase without requesting permission to do so. This is fully legal under the CAN-SPAM Act, but frowned upon by responsible marketers.

• 58% of retailers sent the same first promotional email to buyers and non-buyers alike, squandering the opportunity to personalize or adapt that all-important first message based on the customer's purchase or demographic data.

• Only 15% of retailers used data they received during the purchase process to target promotional messages to buyers.

"Online retailers have become very sophisticated in the art of selling online. Almost every online retailer has some type of email marketing program. However, retailers still struggle to integrate purchase history and customer data to deliver truly personalized and relevant email messages," said Margaret Farmakis, senior director of email response consulting at Return Path. "This type of integration isn't necessarily easy - it requires time, technical resources and marketing expertise. But when done right, it can exponentially increase response rates by making email more engaging for recipients."