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Push notifications have been a godsend for mobile publishers and bloggers. They remind people that there is something important for them to view in an app or on a website they subscribe to. But over time, push notifications can be viewed as spammy, and Spain’s Marfeel is measuring just where that line should be drawn.

Marfeel has launched a data-backed strategy to increase Subscriber Lifetime Value, or the time that someone subscribes to a mobile site or app. Push notifications can help extend the life of a subscriber, but they can also hasten the person’s exit if they’re too, uh, pushy.

Barcelona-based Marfeel said in a white paper released today that its strategy is used to inform an automated framework that can be applied to any publisher, increasing Subscriber Lifetime Value and the website visits and advertising revenue generated by push notifications.

The publisher problem


Above: Marfeel

Image Credit: Marfeel

Now that mobile visitors can account for the majority of publishers’ traffic, push notifications have become a key part of many engagement strategies. (Push notifications are automated messages sent to users of a native app or Progressive Web App to drive visits back to the application when it is not open.)

And push notifications have taken the digital publishing world by storm, Marfeel said. In 2018, a survey found that approximately 19 percent of the publishing and blogging industry has adopted push notifications to drive more traffic, second only to ecommerce websites.

Changes within the publishing industry and their impact on traffic and ad revenue make intelligent automation even more important for digital publishers. In this volatile period, push notifications have given publishers a direct line to their audience, increasing the opportunity to build stickiness and brand evangelism.

Catching the reader at the right time with the right message

Left to right: Dean Takahashi of VentureBeat, Rithesh Menon of Good Media Group, Tony Farrelly of Farrelly Atkinson, and David Webb of Timera Media.

Above: In 2018: Dean Takahashi of VentureBeat, Rithesh Menon of Good Media Group, Tony Farrelly of Farrelly Atkinson, and David Webb of Timera Media.

Image Credit: Marfeel

However, there is a catch. Studies have also found that engagement from notifications wanes over time. And with brand loyalty increasingly driving the survival of publisher websites, optimizing traffic retention using more precise measurements is critical.

Marfeel now delivers automatic push notifications from 123 publishers, who are already using Marfeel features like Google AMP, Progressive Web Apps, and integrations with top ad networks to optimize their mobile performance. The company says publishers generate an average of 6.5 percent of their traffic from its push notification solution, with the highest reaching 20 percent.

The Marfeel study

Marfeel event

Above: Marfeel event

Image Credit: Marfeel

To test the true value added to publishers from their push notification strategies, Marfeel examined the life cycle and behavior of all subscribers.

The company created a series of controlled experiments over 5 million push notifications between November 2018 and January 2019, using a new, isolated metric for digital publishers: the Subscriber Lifetime Value (SLTV). (SLTV is the average total traffic generated by a user from push notifications using a set strategy.) The experiments were designed to isolate the factors that maximize this value.

Marfeel developed a metric that measures the total value of a push notification strategy rather than the isolated impact of push notifications. To develop this metric, the company had to consider the natural degradation of a subscriber’s level of engagement and the interaction with push notifications that occurs despite the push notification strategy applied.

On average, the click-through rate decreases by a factor of 0.4 from the first week to the fifth week. This means that if the click-through rate is 1 percent at week one, in week five it is at 0.4 percent.

The Subscriber Lifetime Value (SLTV) is the average amount of site clicks a subscriber will add before unsubscribing or no longer reacting to push notifications. This metric operates under the proven principle that subscribers have a finite lifespan and a finite value for publishers.

Consequently, Marfeel was able to measure this lifespan and optimize the value that can be earned from it. Short-term optimization of push notifications can demonstrate superficial success while having a negative impact on final value. Optimizing using SLTV, publishers are able to increase the long-term value of their strategies, rather than chasing repeated short-term successes.

SLTV also allows publishers to project the impact alterations to their strategy will have, rather than working retroactively. A strategy that sends one message per day may result in a CPU of 2.18 percent and a USR of 0.213 percent. As with all subscribers, the engagement level, or likelihood of clicking, will naturally reduce, and the likelihood of unsubscribing or becoming inactive will increase as the strategy continues.

Factoring in these effects, it becomes clear this strategy will produce an SLTV of 3.09 clicks. By increasing the message intensity to eight per day, the USR is pushed to 2.24 percent but the CPU also increases to 8.84 percent, resulting in an increased SLTV of 3.35 clicks.

Different strategies may produce results that increase ‘negative metrics’, such as the USR. However, by using SLTV, publishers can see the total net of the value of their strategies.

Intensity and engagement

Above: Marfeel

Image Credit: Marfeel

To measure intensity, Marfeel delivered and tested 650,000 push notifications. The subscribers were split randomly and evenly into four groups, with each group receiving an increasing number of notifications per day.

Results demonstrate the logical result that the CTR decreases as more frequent messages are sent. The unsubscribe rate also increases in line with the number of messages sent. By measuring SLTV, the company was able to determine the optimum frequency of notifications for publisher value.

Marfeel then applied the same bands of intensity to groups segmented by their engagement level. The results of this combined strategy demonstrated a relative increase of 40 percent in SLTV, compared to the control group, in which all subscribers were sent a fixed number of messages per day. Marfeel also personalized the messages and optimized them for delivery at the right time of day. The best time to send messages turned out to be 9 p.m., based on tests of 2 million messages. As part of the test, Marfeel added levels of priority to each message.

The experiment based on intensity and engagement showed that optimizing the number of messages per user, combined with increasing intensity for the most engaged users, will increase the Subscriber Lifetime Value by 40 percent, compared to sending a single message per day.

Personalization of articles using a proprietary recommendation engine demonstrated that sending personalized recommendations can increase SLTV by approximately 20 percent.


Although more forceful tactics can lead to improvements in short-term revenue for publishers, employing these technologies at the expense of the user experience is bound to backfire. In the long-term, it will almost certainly damage publisher brands and undermine readers’ trust.

To complicate matters, single-message metrics such as subscribers or click-through rates cannot be considered valuable long-term commodities for digital publishers. Since push notification engagement wanes the longer a user is subscribed, such metrics do not accurately demonstrate how a wider push notification strategy is performing. Ultimately, push notifications require a measured strategy built to maximize final value for the publisher: website traffic and revenue.

Marfeel says its push notification experiments conclusively reveal that SLTV (Subscriber Lifetime Value) is the metric needed to compare the impact of multiple push notification strategies and modifications.

The study also shows that subscribers will consistently gravitate toward unsubscribing or becoming inactive. However, engaged users are more receptive to more frequent messages and users are generally more resilient to receiving push notifications than first assumed. Unsurprisingly, a system that personalizes push notification content and strategies based on individual user behavior improves both the user experience and SLTV.

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