Email marketing is still one of the most efficient ways to target customers and drive conversions. But like many other marketing channels, data collection and targeting are getting increasingly difficult. Here are five charts summarizing the state of email marketing.

1. Email is one of the most important marketing platforms

Email ranked higher than marketing automation, customer data management, and personalization as tech that marketing professionals are investing in, according to MoEngage and ClickZ.

One reason marketers are focused on email: It’s cheap. According to Litmus, for every $1 marketers invest in email marketing, they can expect a $36 ROI.

2. Email is a leading marketing tactic for B2B

Some 36% of B2B professionals use email for B2B marketing, more than have implemented paid social, virtual events, and video marketing, according to Sagefrog.

Despite its popularity, email marketing will account for just 0.2% of US digital ad spend this year, for a total of $667.3 million, according to our forecast. The low spend figure once again points to how relatively inexpensive email marketing is.

“Email is the only channel that you can put very little effort into and still make money,” Ryan Phelan, managing partner at RPEOrigin, an email-focused marketing agency, told us.

3. Email marketing campaigns face challenges with engagement, measurement

US marketing professionals are focused on increasing engagement and effectively measuring the ROI of emails, according to Ascend2 and OMI data. With the fading reliability of open rates, email campaigns are harder to measure than they were a few years ago, but they’re still effective.

The same Ascend2 and OMI study found that 46% of marketers consider clickthrough rates effective, while 42% prioritize ROI and 36% focus on conversion rates.

4. Email isn’t everything

Email marketing has lost share to push messages and SMS, according to Salesforce. But don’t shift priorities entirely: It can be harder to reach consumers via SMS because they may be more willing to give away their email address than their phone number.

What’s most important is a cohesive marketing strategy across platforms. Consumers don’t want to see the same message replicated across text messages and email. If you’re hitting the same customer twice, make sure messaging is not repetitive.

5. Email is still preferred for receiving deals

Email is far from dead when it comes to deals, according to CouponFollow. Nearly half (48%) of US millennials actually prefer it to mobile app and SMS coupons. The preference for email over mobile apps means marketers may miss out on some of the first-party data that apps provide, but it also means that one of the cheaper options is also the most popular.

With marketing budgets tightening and consumers looking for discounts, focus on email to promote sales and other offers.

Read our other email marketing tips here.

This was originally featured in the eMarketer Daily newsletter. For more retail insights, statistics, and trends, subscribe here.