ESP, CDP, or AI Engine? What Each Tool Should Actually Do in 2026

Martech Stacks Are Evolving—Fast

The martech stack is a marketer’s greatest asset. While every brand’s stack looks a little different, there are three tools every modern marketer interacts with daily: their ESP, CDP, and AI engine. 

But as these tools become more sophisticated—and their capabilities increasingly overlap—it can be challenging to know which ones are truly essential.

Here’s how to clarify what each tool should deliver by 2026, and how to future-proof your stack so it’s both efficient and effective. 

The Modern ESP: From Delivery System to Experience Platform

When ESPs (email service providers) first came on the scene, the goal was straightforward: send bulk and batch emails with a couple of clicks. Soon, additional features like basic segmentation, performance tracking—simple metrics such as opens and unsubscribes—and list management were added to the mix.

But nowadays, marketers can, and should, expect far more from their ESP. Your choice of ESP shouldn’t be a glorified mail dispatcher, but a source of sophisticated deployment and personalization: 

• Advanced Personalization: The ideal ESP will ingest behavioral data and preferences from customers, all while running that data through predictive analytics to create personalized email content. 
• Flexible Integration: The average enterprise brand has 90 tools in their tech stack. No tool can accomplish every marketing task, making it critical  for your ESP to work hand in glove with other apps and tools.
• Always-On Testing: From subject lines to hero images, different email elements should be automatically tested and optimized to keep engagement rates climbing.
• Omnichannel Orchestration: The term “ESP” may stand for “email service provider,” but in today’s marketing world, your ESP should be able to deploy campaigns across all customer channels. 

While your ESP should include all of these capabilities, it’s also important to note what your ESP shouldn’t be claiming. For example, if your prospective ESP defines personalization as listing the customer’s first name in the subject line—and that’s it—it’s time to set your sights on another vendor. 

The Modern CDP: From Data Warehouse to Real-Time Activation Engine

CDPs (customer data platforms), as the name suggests, were initially used as a central hub to unify and store data. As marketers’ digital warehouse, it acted as the one-stop shop for accessing customer data to use for campaign content. But today, your CDP should go beyond its role as a simple online storage unit:

• Audience Activation: Segmentation based on stale data and pre-defined, basic demographics isn’t enough to power engaging personalization. Seek a CDP that enables real-time segmentation and adapts to your customers’ evolving preferences and actions.
• Actionable Data: Marketers need to store data, but if it isn’t used quickly and efficiently, your campaigns will never reap the benefits. Data in your CDP should be accessible and actionable for the rest of your martech ecosystem.
• Robust Compliance: Laws and governance around brands’ usage of data are tight—as they should be. Your chosen CDP should be in line with the most stringent of rules and always manage customers’ consent with care.
• ESP/MSP Integration: No tool should own your entire tech stack. Every campaign needs a strong data foundation, making it crucial that your CDP works with all of your deployment and delivery tools.

These are non-negotiables for a CDP that can keep up with today’s campaign standards. If your current CDP is only housing data and constantly needs IT intervention for operation, it’s time to pivot. 

The Modern AI Engine: From Auto-Segmentation to Performance Booster

AI is on every marketer’s radar right now. Nearly every tool in marketing is claiming to use AI, and they are—but not necessarily in the way you need or want.

If AI is a single feature in your ESP, re-branded rules-based automation, or just a buzzy “content generator” that’s virtually ChatGPT, you’re not actually capitalizing on AI’s limitless potential. Your AI base may not be covered just because your existing tools are adding in minimal AI. A true AI solution needs to include:

• Autonomous Optimization: From creative assets to frequency and send time, your AI should be constantly learning from previous sends and adapting future campaigns based on customer signals—all in real time and without manual intervention. Think of it as an automatic, always-on engine.
• Constant Learning: As customers’ individual preferences and needs evolve, AI solutions must use a combination of existing content, data, and current contexts to deliver campaigns that resonate with audiences today while supporting stronger loyalty and retention.
• Agentic Campaigns: It’s one thing for AI to automatically analyze and power content decisioning, it’s another for it to execute tasks for the marketer within pre-defined rules and parameters. The best AI engines will include this major time-saver, freeing marketers for other strategic tasks.
• Augmented Workflows: While Agentic Campaigns are a key addition to your AI solution, that doesn’t mean it replaces the marketer. To make the most of AI, use Agentic Campaigns to complete tasks that are already set while your team brainstorms strategy and creative ideas.

Don’t get lost or overwhelmed by the constant AI buzz. Look for vendors that bring real value beyond your existing tools’ capabilities.

How ESPs, CDPs, and AI Engines Should Work Together

With these capabilities for each tool in mind, it’s clear that marketers need all three to power competitive campaigns. But in the market, the features for each will certainly overlap, making it more challenging to choose the right combination for your unique tech stack.

The rule of thumb to keep in mind is modularity, not dominance. When each tool can interoperate with the rest of your stack, your workflow will run quickly and efficiently—a must when dozens of campaigns need to get out the door every week. On the other hand, if a tool locks you into their ecosystem and prevents collaboration with other solutions, that’s a problem that will only worsen over time. As technology develops, your tech stack must also be able to adapt. 

But how to find the perfect vendor for each tool? Here are some key questions to keep in mind when shopping for an ESP, CDP, or AI engine:

• How does your platform work with the other tools already in my martech stack?
• Is your AI self-learning or rules-based?
• How quickly can I activate insights from my CDP into real, data-driven campaigns?
• How is customer data protected?
• What kind of performance results can I expect within the first month/quarter/year?

Craft a Martech Stack That Serves You Strategy 

As the marketer, you know what your brand’s KPIs are and what customers need to see to reach those goals. Don’t get lost in the overlapping claims of tech tools—solidify what each solution should accomplish, how they can work together, and what impact they’ll have on your campaigns. A great place to start that search? Movable Ink’s expansive partner network.

A solid ESP, CDP, and AI engine are only part of the puzzle. Discover other ways you can augment your personalized campaigns by booking a call with us and reading the related resources below.