Most marketers have personalization strategies in place, but many struggle to make them effective.

In a March survey from Evergage and Researchscape International of 300 marketers, 93% of whom were from the US, just 6% of respondents gave their personalization efforts an A rating. Some 46% graded their personalization as a C, making it the most popular response given. This implies that marketers’ personalization efforts are good enough for a passing grade—but just barely.

A major roadblock that derails effective personalization is inadequate data. Most of the marketers polled said they did not have sufficient data to mount successful personalized campaigns. Business-to-business (B2B) marketers were more likely than business-to-consumer (B2C) marketers to say their personalization data was insufficient.

The idea of targeting messages that specifically cater to particular users may sound appealing to many marketers, but the technical obstacles make it difficult to accomplish. Sailthru surveyed 146 UK and US marketers in October and found that 37% cited data and technology challenges as a hindrance to their personalization goals.

Marketers are focusing on personalization because many find it to be essential to delivering a solid customer experience. In a January survey of 200 US senior decision-makers conducted by Verndale, nine in 10 respondents said that better personalization was key to improving the customer experience.

But marketers looking to improve their personalization should tread carefully, since a zealous demand for better and more effective personal data can place a firm in hot water. With the upcoming enforcement of the General Data Protection Regulation (GDPR) later this month, and the ongoing scandal with Facebook and Cambridge Analytica, people are becoming more skeptical of sharing data through third parties. And for some consumers, personalization can indeed get too personal.