Building a safer email ecosystem: Insights from Julia Janssen-Holldiek

In the fast-evolving world of email marketing, maintaining trust, deliverability, and compliance is more challenging — and more crucial — than ever. That’s why Stripo sat down with Julia Janssen-Holldiek, director of the Certified Senders Alliance (CSA), to explore the role of certification, digital responsibility, and data transparency in building a safer and more effective email ecosystem. 

In this interview, Julia explains why CSA certification is more than a deliverability boost — it’s a commitment to quality, transparency, and user protection. She shares common pitfalls senders make when relying on assumptions instead of data, emphasizes the growing importance of domain-level monitoring, and offers actionable advice for marketers looking to protect their email reputation in an increasingly complex landscape.

Julia Janssen-Holldiek has been with the CSA for 10 years, serving as its director for the past seven. She has extensive practical experience in self-regulation within the email ecosystem. Before joining CSA, Julia worked in sales and marketing at DELL GmbH. With over a decade of experience and a clear passion for making email better, Julia offers a practical and forward-looking perspective on what brands and email service providers need to succeed today — and tomorrow.

Building trust in the inbox: How the CSA has evolved to keep email safe and effective

Stripo: What initially drew you to the field of email marketing, and what keeps you passionate about it after a decade at the Certified Senders Alliance?

Julia: The Certified Senders Alliance is all about making email better. We create and enable quality standards that help protect users from spam and phishing. Our environment is continuously changing, so it never gets boring, but it is challenging to keep up with the pace. I really appreciate this challenge and the deeper meaning of my job in helping to protect users and promote email as an open and decentralized communication channel.

S: The Certified Senders Alliance plays a significant role in the email ecosystem. How has its mission evolved over the years, and what are the biggest challenges it addresses today?

J: Our mission has not changed in the last 20 years. The CSA was founded based on the need for senders and mailbox providers to create a trusted and protected channel in the email ecosystem. The criteria and challenges have changed significantly over the years. We started with nine criteria in 2004, and now our criteria catalog consists of nine pages due to the increasing complexity of sending emails. The responsibilities of senders have also shifted, from detailed legal requirements toward technical requirements that ensure the protection of a sending platform.

Deliverability and reputation: Why data-driven monitoring is your best friend

S: What are the key benefits of email certification for senders, and how does CSA certification specifically impact email deliverability?

J: In the future, we will differentiate between IP and domain certification. The existing IP certification enables senders to be identified as trusted senders by (potential) customers and mailbox providers, with related benefits in email deliverability. Furthermore, certified senders are provided with real mailbox provider data (e.g., spam click rates, and DKIM errors), enabling them to monitor their customers and their quality of sending and even identify potential bot attacks — all of which are highly relevant for ensuring future deliverability.

S: Some email marketers question whether certification is necessary in 2025. How would you respond to those who believe they can achieve strong deliverability without it?

J: Senders can definitely achieve strong deliverability without CSA certification. They just need to have the right monitoring with the relevant data in place and a very good network. If they lack one of those aspects, the CSA is here to help. Certification is becoming increasingly relevant for mailbox providers as a sign of trust and commitment from senders in times of increasingly complex filtering.

S: Maintaining a strong email reputation is crucial for inbox placement. What are the most common mistakes senders make that damage their reputation, and how can they avoid them? What are the most effective ways for senders to proactively improve and protect their email reputation?

J: This is a very complex topic. I wouldn’t like to focus on one particular mistake that is likely to ruin reputation. It is more about the general problem that senders often rely on their assumption that they have the right mechanisms in place rather than actually looking at real data. 

One example: During the certification process, we see senders who think their DKIM is correct until we show them otherwise. We show them how it is seen from a mailbox provider’s perspective.

S: What key strategies should brands implement to ensure that their transactional emails reliably land in the inbox rather than spam or promotions folders?

J: The baseline requirements are: 

• authentication; 
• listening to user feedback (positive and negative engagement);
• looking at the mailbox provider information; 
• monitoring process in place.

S: How do mailbox providers assess email trustworthiness, and what role does CSA certification play in improving sender reputation?

J: Mailbox providers use different signs of trustworthiness to make their filtering decisions. They also handle these decisions very differently, depending on their capabilities and preferences. Nevertheless, there are basic common requirements, recently published by Google, Yahoo, and Microsoft. 

Mailbox providers use the CSA certification as a sign of trustworthiness, as they know the sender has committed to transparency and adherence to these best practices despite the paperwork involved. This trustworthiness is rewarded by mailbox providers with a more reliable delivery of emails and the provision of relevant data. Senders can access mailbox provider data via the CSA Certification Monitor and thus prevent future deliverability issues.

From ethics to inbox: Why responsible email marketing drives long-term success

S: You’ve spoken about the importance of digital responsibility in email marketing. What does that look like in practice, and why should brands prioritize it?

J: Companies need to respect basic user privacy principles in order to build relationships with their (potential) customers in the digital world. Basic principles, such as being clear and transparent, taking over responsibility, and processing data ethically, have been tailored to the email world in the CSA criteria. The CSA criteria are precise and hands-on recommendations for senders to ensure that they are acting responsibly in the field of email. Brands should prioritize this, as it will otherwise have a negative impact on their ROI.

S: How does the CSA help senders minimize risks with dedicated warnings, and what are the most critical red flags marketers should monitor?

J: The CSA displays red flags in the Certification Monitor and within email alerts. Senders also receive feedback on individual user complaints from our CSA complaints office. If a certified sender is getting close to certain thresholds, our account management team will contact them with a heads-up. If thresholds are exceeded, our complaints office will take action. 

S: What issues can senders identify using CSA data, and how can they use this information to improve deliverability?

J: Senders can identify problematic customers through reports from our complaint management team and the spam click rate in the Certification Monitor. Based on these data, they can educate such customers on how to improve their sendings or decide to remove them from their platform in order to protect the sender’s overall reputation. Moreover, ESPs can identify issues with their DKIM, DKIM alignment, spam traps, and metrics, such as their overall spam click rate and the evolution of their inbox placement rate over time.

S: How do you envision email marketing evolving over the next five years, and what role will CSA play in shaping that future?

J: The CSA will expand its service to include domain certification for brands, as mailbox providers are already taking domain reputation into account in their filtering decisions. Brands that send through an IP-certified platform will be able to show their trustworthiness to mailbox providers at the domain level and receive even more detailed data, such as their inbox placement rate. 

The CSA will provide certified brands with real mailbox provider data that can be used to monitor deliverability and ensure future deliverability. The value of this data is increasing as access to data becomes more complex in times of moving legal landscapes, and traditional KPIs such as open rates are getting blurred due to non-human Interactions. 

Wrapping up

We are incredibly grateful to Julia Janssen-Holldiek for sharing her deep expertise and practical insights with us. She clarified the challenges and responsibilities that modern email marketers face and offered actionable guidance for navigating them successfully.

Here are some key takeaways from the interview:

1. Monitoring and data are essential: Many senders rely on assumptions about their infrastructure or processes. Julia emphasized the importance of using real data and feedback from mailbox providers to ensure ongoing deliverability and reputation management.
2. Digital responsibility is a competitive advantage: Acting transparently, respecting recipient privacy, and taking accountability for data handling aren’t just legal requirements — they’re essential for building long-term relationships and protecting ROI.
3. The future of email lies in domain-level visibility: As mailbox providers shift toward domain-based filtering, domain certification and deeper monitoring will become critical tools for brands aiming to stay in the inbox.
4. Certification builds trust and improves deliverability: CSA certification helps senders demonstrate their commitment to responsible email practices, giving mailbox providers clear signals of trust and providing access to valuable deliverability data.