IoTDomainReputationThe “Internet of Things” (IoT) essentially describes the communication between countless devices via the Internet. The concept is well known by now and will become a reality with billions of more connected devices to the Internet in the coming years. The chances of abuse increase immeasurably: on the one hand, completely new options for communication and transactions with your customers open up; on the other hand, the dangers increase, because spammers and phishers know how to use these new options against you and your brand.

The concept of IP addresses as the interface between computers and devices with the Internet is well known. For years the business world and information technology used a certain version of IP addresses, namely IPv4, without worrying about the fact that the number of possible IP addresses is finite. The IPv4 variant has a total of 4.3 billion addresses and with the steady growth of computers and computing devices connected to the network, the IPv4 addresses will be assigned. To create a way out, the Internet Engineering Taskforce (IETF) created a new IP standard in 1998: IPv6. The number of possible IPv6 addresses is unimaginably large, in the range of several hundred quadrillion, so it should be sufficient for some time.

As for email marketing, your reputation as a sender today is primarily related to your IP address. As the introduction of IPv6 addresses progresses, it will no longer be possible in the foreseeable future to evaluate the sender reputation in the IPv6 version solely in terms of the IP address. As a result, the domain is increasingly becoming the focus of attention as a reliable assessment criterion for reputation.

Return Path, refers in this context to DomainKeys Identified Mail (DKIM) and to the following aspects, explaining why the domain reputation is becoming increasingly important for mailbox providers:

  • The Domain-based Message Authentication, Reporting, and Conformance (DMARC) standard is increasing the interest of mailbox providers in the DomainKeys Identified Mail (DKIM) test. And if DKIM checks are carried out anyway, the domain reputation continues to gain in importance.

  • Mailbox providers face the fact of emails with IPv6 addresses. IPv4 blacklists and reputation services are very effective, but in a world determined by IPv6, senders can hide more easily, so that IP-based blacklists are no longer an effective means. The reputation of domains, however (just like whitelists with IPv6 addresses and domain whitelists) can work in the IPv6 world.


Of course, IPv6 will only be introduced gradually and the merging to the "Internet of Things" is no small matter, so you can most probably still use your current IP addresses for quite some time. In the foreseeable future, mailbox providers will continue to use a combination of IP and domain reputation as a basis for decision-making. Spoofing is also still a weak point of domains, and it will take time for more effective domain reputation protocols to be developed and implemented. To protect your own reputation as a sender in this transition situation, the following measures are recommended:

1. Track your IP reputation using, for instance, tools like Sender Score and Inbox Monitor from Return Path. You can also initiate monitoring of your domain(s). Start by applying complaint rates, unknown user rates and other metrics that you use to control your IP address(es) to your domain(s). If some of your sending IPs have bad reputations you should be careful, as this could damage your entire domain reputation.

2. Make sure you authenticate using SPF and DKIM. If you haven't already, get started right away.

3. Consider using DMARC.

4. Keep the number of your domains as low as possible, considering the requirements of your email program. Having many domains makes it easier for spammers and phishers to pass off fraudulent emails as originating from your brand. At the same time, it makes it difficult for you to track down these attackers to stop them.

5. If you send emails through domains of service providers, you must also track the performance of the email campaigns and email streams running from these domains. You may unwittingly identify yourself as a potential spammer if such domains appear on blacklists or are associated with spam.

6. Check domain blacklists such as SURBL, URIBL and Spamhaus DBL regularly to make sure your domains are not listed there. If one of your domains is listed, determine the cause as soon as possible so that you can fix the problem and do not appear on these lists again.

7. It is advisable to refrain from affiliate marketing. A partner who uses your domain to send emails can cause your domain to be blacklisted and damage your reputation as a sender, which can lead to delivery problems for your own e-mails.

The fact is that the reputation of your domain is already an indicator of filter decisions for mailbox providers. And the more computing devices are connected to the “Internet of Things”, the more important the domain's reputation becomes. With billions of other devices connected via the Internet in the next 5 years, the chances of misuse increase immeasurably.

By MediaBUZZ