March 2021 - Email Marketing | Email

A New Way of Thinking – Email Sender Certification 2.0

Sebastian Kluth from the CSA outlines the evolution of attitudes in email marketing, and the changing deal between email marketeers and mailbox providers.

A New Way of Thinking – Email Sender Certification 2.0

© EtiAmmos |

Ever since it first emerged as a communication tool, the purpose of email has been to have itself delivered into the inbox of the recipient. Having started out as an individual and personal communication aid for a small group of people, it has evolved into a mass communication tool. New ways to manage the increasing volume of emails were needed. The main development moved in two directions:

  1. Further evolution for communication between two individuals
  2. Bulk sending services that developed into modern Email Marketing

With the growth of Email Marketing and the related goals of higher effectiveness and generating more revenue, new challenges appeared.

While in the past the email user received just a few emails per week, we can nowadays see hundreds of emails coming in every day. This has resulted in a change in attitude of the recipient to unwanted email messages. In the early days, the definition of Spam was “unwanted email received without asking for it” or “unsolicited commercial email”, whereas the term’s usage today has transformed into the subjective judgment of the user feeling overloaded by the incoming email volume or badly treated by the senders – even if the user is actually subscribed to a legally-compliant mass emailing list.

Mailbox Providers’ priority is to protect their users

The sending frequency, the content relevance, and the targeting – and even external factors like the general reputation of the brand in question – are influencing the subscriber’s assessment of whether an email constitutes spam or not. This makes email management and deliverability even more important than it was 15 years ago and creates new demands for all players in the ecosystem.

To help the email user to manage their inboxes and suppress unwanted email, over the last couple of years mailbox providers have implemented filters and rules of engagement. They have learned to distinguish between good and bad email from user feedback. Content keywords were initially the most obvious factors – but this was just the beginning. Today, the evolution of tracking, automation, and machine learning have resulted in the Mailbox Provider starting to include and consider even more data points like reads, filing, forwarding, or other email interactions. Email Filtering is becoming a more intelligent and complex process based on an extensive list of complex rule-sets and dependencies. Having the correct SPF record in place – a good place to start, perhaps – is by no means enough to reach the inbox anymore.

Taking a new approach to good and bad in the email world

In the mindset of some market participants, the email world may appear to be easily divisible into good and bad. For many email marketeers, the mailbox providers are the bad guys who only want to stop them from earning money with email marketing. However, it is not as simple as that, and this oversimplification does not reflect reality.

The evolved complexity of email deliverability and the related challenges of constantly increasing global email fraud is putting enormous pressure on mailbox providers. It is not easy to distinguish between bad and good. Consumer behavior has changed over the last few years, and mailbox providers are challenged to consider and respect this user behavior and feedback.

Only a minority of emails are filtered on the basis of dedicated block-listing. The current email filtering technology is based on learnings from the past days, weeks, or month, analyzing content and related user behaviour, as well as from continuously listening to feedback from recipients. For marketeers, this has led to the necessity for a new way of thinking about certification and the willingness to listen to and take seriously the voices and best practice advice of the mailbox providers, as well as the use of positive IP or domain lists.

Certification 2.0 – the emerging two-way model for email optimization

Today, certification and IP lists are no longer tools that automatically guarantee hundred percent inbox delivery. Many email marketeers still think that participation in a certified list is about their payment and a resultant commitment by the mailbox providers to accept every single email regardless of content or practices – but this has become an outdated model.

Today, Spam fighting focuses more on reputation. Technical requirements like SPF, DKIM, and DMARC are just the basics which must be followed. Decisions on whether to deliver an email into the inbox or the spam folder are made on the basis of the long-term and short-term reputation of the IP and domain. This new style of certification is turning into a two-way model of deliverability optimization, rather than only being the tech tool of a list of IPs or domains. This two-way model means using the IP or the domain as the datakey for receiving exclusive data feedback from mailbox providers to be able to improve the email performance.

Gaining exclusive access to data

The deal between email marketeers and mailbox providers is changing. Rather than getting wholesale delivery into inboxes just on the basis of payment, this is moving to an agreement to commit to best practices and regulations in return for exclusive data insights from the ecosystem of mailbox providers. A Mailbox Provider offers insights about the reputation with data like user feedback, spam clicks, filter results, or differentiated bounce codes.

This new development can be seen in the evolution of data tools and services the mailbox providers have built over the past few years. Free tools like Microsoft SNDS or Gmail Postmaster Tools already provide data insights into the Mailbox Provider’s world. Furthermore, participants of a certified list will be part of an exclusive group of senders who gain an even deeper level of insights than senders who are not on the list. Even local mailbox providers such as 1&1 Mail & Media (GMX, and or Swisscom have started to provide data feedback through dedicated partnerships.

The commitment of the sender to follow best practices and the strong membership criteria of a certification program are the key to getting these deeper insights. The benefit is targeted reputation and deliverability management using the data insights. The resulting improvement in performance will provide benefits for a better and preferred inbox placement, as this improvement meets the Mailbox Provider’s expectations.

Domain reputation becoming key

Looking at the email world today, it seems that the abstract technical email world is becoming a little more natural. Why? Reputation measurement and data collection are built upon the domain basis, rather than only on IP level. Just to give you one well-known example: the Gmail Postmaster Tools do not even require the submission of IP addresses – it pulls the sending IPs automatically from the domain. Another example is the Verizon Media feedback loop, which is completely built on the DKIM (DomainKeys Identified Message) domain.

What is the result of this? It means it is no longer possible to just switch IPs to reset the bad reputation and proceed with sending the same traffic. It is a much bigger hurdle for a serious sender to switch the sending domain, because the domain is often a kind of personal name or includes the brand image and identity.

Reputation building and maintenance will further shift from IP to domain. Senders who maintain their reputation from all perspectives on a domain basis will benefit from a long-term deliverability and email marketing success. Senders who often switch IPs and sending domains at random will be treated with suspicion. This is a natural reaction, if you think of it like this: Someone that I have already known by name for a long time is a person I can trust a lot more easily than somebody I just got to know the name of recently, even if my long-time contact has moved houses in the meantime.

You may change systems or IPs, but if you keep your domain name and you care about it, you will earn long-term benefits through trust. Therefore, I believe certified domains are the next logical consequence in the email sphere. This is already available in the market and demanded by mailbox providers, but it is time to get it rolled out on a broad level. But the deal between the mailbox providers and email marketeers will remain the same as before. It may also shift the responsibility about reputation from the Email Service Provider, as the owner of the IPs, to the sending brand, who owns the domain.

Making data insights actionable

Email deliverability requires a strong, reliable, and transparent partnership between senders (Brands and email service providers) and receivers (mailbox providers). It requires a change in the mindset. The notion of bad mailbox providers versus email marketeers is the wrong view. Instead, it is all about reputation and protection of the valuable email user – this attitude will help to find open- minded ways to increase email business success and growth while following best practices.

IPs as the central item of reputation management will disappear and the domain will move to center-space, not only because IPv4 is becoming increasingly limited, but also because the domain is the key item to represent a brand’s reputation in the long term.

Marketeers should take care of their reputation and maintain it by making use of the exclusive deliverability insights of being part of a certification. The mailbox providers will continue and increase their offers with regard to sharing data in exchange for the serious motivation of senders to reduce spam and applying best practices. They will increase their data analytics and offerings for senders and specialized deliverability, while certification vendors will translate this exclusive data into actionable recommendations for email marketeers.


Sebastian Kluth is an email marketer through and through. Since September 2019 he has been working as Technical Lead CSA for eco – Association of the Internet Industry in Cologne. As an experienced expert of many years’ standing, Sebastian Kluth advises customers and senders on individual solutions in the fields of email marketing, email deliverability, and email response optimization.

Most recently, the qualified computer scientist worked as Team Lead & Senior Email Strategist at Return Path. Before that, he worked in various fields and functions of email marketing with the netnomics agency, with Gruner & Jahr’s German press distribution, with Emailvision, and with Otto GmbH & Co. KG in Hamburg.