Email Domain Warmup for iGaming: Best Practices

Email marketing isn’t dead — it’s doing just fine. B2C marketers even reported it as their top channel for ROI in 2024. But to get the most out of it, you need a proper email domain warmup, especially in iGaming. Without it, operators risk having their email blacklisted or filtered as spam. This drags down marketing effectiveness and can even (as our team has seen) lead to the domain rate dropping to zero.

As Head of VeliEDGE, I’ve spent years helping operators worldwide improve their engagement strategies. While I’m a strong advocate for an omnichannel approach, email is one channel that requires particularly careful planning. Our collaboration with BlueChip has highlighted how crucial proper domain and IP warmups are for successful email marketing. 

This article breaks down the key factors influencing domain reputation and shares proven warmup practices tailored for casino and sportsbook brands.

The effectiveness of email for player engagement depends on where your market lies. For example, email marketing is perfect for markets with widespread desktop usage and connectivity. 

According to Statista’s 2024 report, users in the United States send 9.7 billion emails daily, which is the highest volume globally. It’s followed by countries like Germany, Ireland, and the Netherlands. Several Asian countries also rank in the top 10, including Japan and India (8.2 billion each).

This isn’t just theory — it’s what we’ve seen work in practice for our clients. For example, the email channel performed well for Rival Fantasy in the USA and Europe, and proved especially effective for BlueChip in India. 

In contrast, when we helped CASONGO launch in Africa, we found that players were less receptive to emails. Many areas of the continent have poor Internet connectivity, and players prefer messaging apps and SMS.

The takeaway? Research your players’ regional preferences to build appropriate engagement strategies. If email proves to be a strong channel in your target market — congratulations, this article is for you. Like any engagement channel, email requires a tailored approach. But unlike most, it demands more deliberate preparation to perform at its best. That’s why many of our clients turn to us for guidance on how to get it right. So, let’s dive into one of the most essential steps for making email marketing work in iGaming: a proper warmup strategy.

Email warmup is the process of gradually increasing the sending volume from a specific email address to build a reputation with email service providers (ESPs), such as Google Workspace and Yahoo. Warmup helps an ESP see positive engagement from your account (opens, clicks, no spam complaints), which improves your reputation (trustworthiness) as a sender.

Domain email warmup extends warmup to all email addresses under your domain. It involves incrementally increasing the send volume across multiple mailboxes to build ESP confidence in your domain.

Domain reputation or domain rate (DR) is a score that email providers use to measure how trustworthy your domain is. To run a successful email campaign, iGaming platforms should have a strong DR score with low spam complaint rates.

Domain warmup can make or break the ROI of any marketing campaign. Yet, it’s even more demanding in iGaming due to high sending volumes, stricter content policies, and increased scrutiny from email providers. 

Benefits of warmup:

• Reduces the risk of triggering spam filters. Learning how to warm up a new email domain is essential to avoid ESP blocks and spam filters. The domain warmup strategy allows you to maintain a pattern of consistent, human-like sending behaviour. This, in turn, makes your messages seen as legitimate.

• Ensures compliance with ESP regulations. ESPs are also extra careful about emails that promote gambling-related services. A gradually warmed-up domain establishes trust with email service providers and signifies that you follow best practices.

• Strengthens trust. Warmup also protects your brand from being flagged as a spammer or scam operator, which is especially important in regulated environments. A credible domain, complete with recognisable sending addresses and authentic branding, reassures players that your messages are safe and worth opening.

In short, domain warmup is more than just a technique to avoid spam filters. It can help your platform consistently deliver timely offers, news, and personalised messages to players, leading to higher engagement and revenue.

Judging by my experience at VeliTech, some casinos and betting brands misunderstand how domain reputation works. As a result, they overlook a huge opportunity to improve campaign ROI. Let’s go through the essential factors that affect your domain’s authenticity.

Operators often ask why their emails underperform. My first question back: “How’s your spam rate?”

The answer is smaller than most expect. Surprised? Many operators are — until their campaigns tank. Let’s make sure yours doesn’t.

Spam complaint rate reflects how often your recipients mark your emails as spam. ESPs, especially those working with tools like Spamhaus and Barracuda, monitor complaint volumes and user behaviour closely. Frustrated players who get too many emails may report your messages, and the more complaints you get, the higher your spam complaint rate.

When that rate climbs too high, your emails may stop reaching inboxes or even get you globally blacklisted. A rate of 0.1% or higher — that’s just 1 complaint per 1,000 emails sent — is already enough to raise red flags with most email providers. For best deliverability, you should aim to stay well below this threshold.

It’s worth noting that some platforms also display visual spam indicators, like a score of 7+, 70%+, or a red status, but these often refer to internal scoring systems, sometimes called spam scores, and may vary. 

A bounce happens when an email is sent to an invalid or deactivated address or experiences temporary delivery failure due to inbox or server issues. Like spam rate, a high bounce rate affects your domain reputation. If too many of your emails fail to deliver, ESPs can start throttling or blocking your messages. In my experience, a bounce rate higher than 10% and delivery rates below 98% put the domain in the high-risk category.

Engagement metrics reflect how your recipients interact with your emails. 

• A high open rate (ideally more than 20%) tells ESPs that recipients value your messages.

• Click-through rate (CTR) increases when users click on links in your emails, showing that they’re relevant, safe, and trustworthy.

• Reply rate shows two-way communication, which establishes the sender as legitimate.

• Message forwards show that your content is so valuable that readers share it.

Low engagement metrics lead to poor deliverability, while high engagement strengthens your email marketing sender score.

Authentication proves to ESPs that your emails are coming from legitimate domains, not from phishers attempting to spoof your brand. It helps meet compliance requirements, secure communications, and prevent impersonation.

This step is critical in iGaming because platforms send high volumes of marketing and transactional emails, often containing financial data or personal information. Gambling and betting businesses might face strict regulatory scrutiny and frequent phishing attempts, making deliverability less predictable than in other industries.

To help build trust and improve inbox placement, an email domain warmup service will typically configure four core protocols: SPF, DKIM, and DMARC (which verify sender identity), plus BIMI (which displays your brand logo to boost credibility). Tools like DMARCIAN or Valimail also help monitor failures and provide detailed authentication reports.

It’s essential to craft messages for different segments. Tailor your promotions to each customer group instead of sending generic emails. For instance, many iGaming customers, especially in Africa, access email on mobile. Format your emails accordingly, ensuring that messages suit smaller screens and CTA buttons are easy to tap. Also, use email warmup tools with AI-powered personalisation that will mention a player’s recent activity (bets, tournaments, activated bonuses, etc.) and send content based on their preferences.

The content of your emails affects whether your messages are ignored or counted as spam. While generative AI and large language models can help create personalised content for different user segments, human-written emails tend to perform significantly better, especially during the early stages of domain warmup. Here are some other content red flags.

Email providers also analyse your domain history to determine its legitimacy. Typically, new domains are treated cautiously for 60 days after creation. They have a higher chance of blacklisting if initial campaigns trigger too many spam complaints. This is why newly registered domains without a sending history need careful domain warmup. 

ESPs track a sender’s IP address (distinct from your domain) to determine whether the sender is legitimate or untrustworthy. If an IP has a negative history, sent emails may be filtered or rejected.

For iGaming platforms, it’s important to understand the difference between a shared and dedicated IP address for new domains:

• A shared IP address is used by multiple senders, so your email deliverability is affected by their practices. This option may be enough if you’re a small platform with low email volume.

• A dedicated IP address can be exclusively assigned to your domain, giving you full control over your reputation.

With recent launches in South Africa and Asia, we at VeliTech have helped many iGaming companies build brand authority across regions. As Head of VeliEDGE, I’ve overseen many successful marketing strategies and domain warmups worldwide.

That’s why I’ve gathered our top insights into a guide to help you warm up your email domain and be free from spam filters, setbacks, and guesswork.

As a bonus, the guide also includes a curated list of iGaming-specific spam trigger words to avoid.

All in all, a strong domain reputation is critical for email marketing. It ensures your emails reach players’ inboxes and drive consistent engagement instead of getting throttled by your ESP. 

VeliEDGE picks up where warmup leaves off. Once your email domain is warmed up, you can seamlessly launch targeted email or even full omnichannel campaigns through VeliEDGE. Our intuitive, no-code CRM is built specifically for iGaming operators to optimise player engagement, retention, and marketing performance. Drag-and-drop content creation simplifies your workflow, and our customer journey builder streamlines campaign execution from start to finish.

VeliTech empowers casino and betting brands with an ML-driven product ecosystem and expert guidance. Get in touch to see how VeliEDGE can power your player engagement and maximise campaign ROI.