Email remains one of the most important means of communication for companies. But even the perfect email campaign is useless if it doesn’t end up in your recipients’ inboxes. One crucial factor that determines whether your messages arrive or end up in the spam folder is the reputation of your email mailings. In a recent CSA webinar, Sebastian Kluth (CSA) and Melinda Plemel from Spamhaus Technology discussed the myths, truths and fundamental aspects of IP and domain reputation. This article summarises the most important findings for you.

What exactly is IP and domain reputation?

Think of your reputation as a kind of credit score for emails. It signals to mailbox providers such as Google, Yahoo or Microsoft whether a message is trustworthy or not. This reputation is essentially made up of two main factors:

1. IP reputation: This is probably the oldest factor. It assesses the trustworthiness of the technical infrastructure (the server or IP address) from which the email is sent. Mailbox providers check whether the infrastructure is technically compliant, has been properly authenticated and what history the IP address has. This is particularly relevant for shared IPs, as different senders use the same infrastructure and can therefore influence each other.
2. Domain reputation: This factor has become increasingly important in recent years. It refers to the trustworthiness of your specific domain (e.g. @your-company.com). The domain is considered the digital identity of the sender and is often closely linked to your brand reputation. It is crucial in determining whether your email ends up in the inbox or the spam folder. The advantage of domain reputation is that it ‘tracks’ you, even if you change IP address or service provider.

Both types of reputation are closely linked and influence each other. A bad IP reputation can affect a good domain reputation (‘living in a bad neighbourhood’), and conversely, a bad sender (domain) can worsen the reputation of the IP address used.

What factors influence your reputation?

A variety of factors play into your IP and domain reputation. Among those that have the most impact are:

• Your sending history: Have you sent a lot of spam or harmful content in the past?
• Engagement: How is your content received by recipients? Is it being opened, clicked or marked as spam?
• Negative metrics: Complaint rates, spam trap hits, unknown users, etc.
• Positive metrics: Open rates, click rates, redirects, replies.
• Association with malicious content: Have you ever been associated with phishing, malware or suspicious content?
• Age of IP/domain: New IPs or domains may initially be considered more suspicious.
• Authentication: Are your emails properly authenticated with SPF, DKIM and DMARC?

The role of content and recipient engagement

Content still plays an important role. Bad content can trigger spam filters, even if the infrastructure is good. While keyword filters used to be more dominant, today, context and the recipient’s reaction to the content are more important. If recipients react positively to your content (engagement), this sends positive signals to the mailbox providers. Even seemingly critical content (such as the casual dating emails mentioned in the webinar example) can have a good reputation if users expect it and react positively to it.

Challenges for small mailings and the importance of authentication

Small mailings often face particular challenges, especially when ‘warming up’ their reputation. While larger mailings are more accountable and a mistake has a greater impact, smaller senders may have a little more room for manoeuvre, but at the same time feel the impact of a mistake more acutely.

A common problem, especially for small companies, is setting up the domain and authentication correctly. Many start out using generic addresses or don’t know how to set up SPF, DKIM and DMARC. Experts emphasise that authentication is one of the most important first steps. Not only does it help deliverability, but it also signals that you are committed to preventing abuse of your domain. DMARC even gives you the option to tell mailbox providers what to do with emails that claim to be from your domain but are not authenticated (e.g. reject them).

It is worth using a sending address that matches the brand name from the outset and setting up the technical basics properly. Mailbox providers are increasingly looking beyond just email to the credibility of your brand in general (e.g. does a reputable website exist, is value provided?).

What to do if your reputation is damaged?

A damaged reputation is no reason to despair. It can usually be rebuilt, even if it takes time and effort. The important thing is

1. Don’t panic: Take a deep breath and don’t react hastily.
2. Analyse the causes: Find out what went wrong. Eliminating the root cause is crucial, otherwise you will run into the same problem again and again.
3. Check the basics: Make sure you meet the sender requirements of mailbox providers (e.g. Google, Yahoo), that your authentication is set up correctly and that you are using DMARC reports to keep track.
4. List maintenance: Review and improve your list management processes. How do you acquire subscribers (permission level)? How do you maintain the list (removal of bounces, unengaged users)?
5. Segmentation: Focus on your most engaged users first to send positive signals and gradually rebuild your reputation.
6. Don’t change IP/domain immediately: Simply changing the IP address or domain without addressing the root cause will not solve the problem and may make the situation worse, as a new IP/domain will initially have no reputation. An existing, even damaged, reputation is at least known, and it is often easier to build on this.

Conclusion

IP and domain reputation are not mysterious buzzwords, but fundamental pillars for the success of your email communication. They act as a trust signal for mailbox providers and play a key role in determining whether your messages reach the inbox. While IP reputation evaluates the technical infrastructure, domain reputation is becoming increasingly important as the digital identity of the sender.

The good news is that reputation can be established, maintained and even restored. This requires care in technical setup (especially authentication!), list management and the creation of engaging, expected content. Take the time to understand and actively manage your reputation. It’s an investment that will pay off in better deliverability and ultimately business success.

All of us in the email ecosystem – from senders to ESPs to filters and mailbox providers – work together to create a trusted environment. Leverage the resources and knowledge of experts and partners to build and protect your email reputation.

Note:
Check out the full webinar recording of “IP & Domain Reputation: Myths, Truths, and the Basics You’re Still Overlooking” on YouTube