How do top-level domains (TLDs) impact email deliverability and spam filtering?
Michael Ko
Co-founder & CEO, Suped
Published 25 Jul 2025
Updated 19 Aug 2025
6 min read
When managing email deliverability, many factors influence whether your messages land in the inbox or the spam folder. One aspect that often raises questions is the impact of top-level domains (TLDs). These are the last segments of a domain name, such as .com, .org, or .io. While often overlooked, the TLD of your sending domain can indeed play a role in how mailbox providers and spam filters perceive your emails.It is not the sole determinant, but it contributes to your overall sender reputation.
This influence stems from various factors, including historical spamming trends, the cost and ease of registration for certain TLDs, and the general perception that internet service providers (ISPs) and email clients develop over time. Understanding this dynamic is crucial for maintaining strong inbox placement and avoiding the blocklist (or blacklist).
The role of TLD reputation
Mailbox providers and spam filters are constantly evolving their algorithms to identify and block unwanted mail. A significant part of this involves assessing the reputation of the sending domain. Your TLD, alongside other domain health indicators, forms part of this assessment. If a particular TLD has a high historical rate of spam or malicious activity, it might be viewed with increased suspicion, potentially leading to higher spam filtering rates for all domains using that TLD.
This creates a feedback loop. Spammers often gravitate towards cheaper or less regulated TLDs for their campaigns. As these TLDs become associated with illegitimate sending, filters become more wary. This, in turn, discourages legitimate senders from using them, further solidifying the TLD's poor reputation. This is why you might find that some TLDs like .biz or .info have historically faced more scrutiny than traditional ones like .com, even if your domain has a clean sending history. To learn more about this, read our article does a .info domain affect email deliverability.
Newer generic TLDs (gTLDs), such as .xyz, .online, or .top, can also face initial skepticism from filters simply due to their novelty or if they become popular among spammers. Some research suggests that certain newly introduced TLDs have a high percentage of spam or malicious emails associated with them. For example, Cloudflare blog noted that TLDs like .uno, .sbs, and .beauty have had over 95% of their emails flagged as spam or malicious. This can lead to these TLDs being automatically sent to spam or having a significantly higher spam score. You can read more about TLDs and email phishing threats for further insights.
How TLDs influence spam filters
Mailbox providers do not typically publish their exact filtering criteria, but it is known that TLD is one of many signals they use. They analyze vast amounts of data to identify patterns associated with spam and legitimate email. If a TLD consistently shows a high volume of spam, phishing, or other abusive content, it will undoubtedly contribute to a negative reputation for that TLD. This can affect even well-behaved senders using such domains.
The impact can be particularly noticeable for businesses engaging in cold email outreach, where initial trust is paramount. Choosing a TLD perceived as risky can lead to higher bounce rates and direct placement into the junk folder, hindering your outreach efforts. It is always wise to choose a TLD that conveys professionalism and legitimacy. For more on this, check out our guide on how different TLDs affect cold email deliverability.
Risky TLD practices
New or obscure TLDs: Using TLDs like .xyz, .top, or .loan may trigger spam filters due to their association with past spam campaigns. Historically, some of these domains have also been cheaper and easier to register, making them attractive to malicious actors.
Lack of authentication: Failing to implement proper email authentication like SPF, DKIM, and DMARC on any TLD, regardless of its reputation, significantly increases the risk of your emails being flagged as spam. This applies even more to less trusted TLDs.
Recommended TLD practices
Established TLDs: Prioritize widely recognized TLDs like .com, .org, .net, or country code TLDs (ccTLDs) with good reputations. These TLDs generally carry more trust with mailbox providers and recipients. An overview of ccTLD spam statistics can be helpful.
Dedicated sending domains: If you send high volumes of email, consider using a separate domain or subdomain specifically for email sending that maintains an impeccable reputation, distinct from your main website domain.
Even with a well-regarded TLD, consistent adherence to email best practices is essential. This includes maintaining a clean email list, sending relevant content, and ensuring your email authentication records (SPF, DKIM, DMARC) are correctly configured. These elements together build a strong sender reputation that helps override any minor TLD-related concerns. For more information, read our article, how HTML email size, TLD, attachments and domain reputation.
Practical considerations and best practices
When choosing a TLD for your email sending, the safest bet is to stick with established and widely recognized options. While a .com domain is often seen as the gold standard for its universal acceptance and trustworthiness, other traditional TLDs like .net, .org, and even many country-code TLDs (ccTLDs) are generally safe choices, provided your sending practices are solid. To find out more, read our article what TLDs should be avoided.
It is important to differentiate between TLDs for web presence and TLDs for email sending. While a .io or .app domain might be perfectly suitable for a tech startup's website, using it for high-volume marketing emails might introduce unnecessary deliverability risks if those TLDs are seen as suspicious by certain filters. Always consider your email program's specific needs and the potential impact on your email domain reputation.
Ultimately, the TLD is one piece of a larger puzzle. A strong sender reputation built on consistent, legitimate sending practices, proper email authentication, and engagement metrics will always outweigh the choice of an unconventional TLD. However, opting for a TLD with a clean reputation provides a solid foundation and can help avoid an uphill battle against aggressive spam filtering. Read our article, how top-level domains impact deliverability, for further information.
Choosing your TLD
When you choose a TLD, consider its general reputation for email sending, not just for websites. Some TLDs, especially those new or cheap, might have a higher spam rate, leading to greater scrutiny from mailbox providers like Gmail and Yahoo Mail. A .com or .org often carries more inherent trust for email purposes.
Summary
The impact of a TLD on email deliverability is a nuanced topic. While a good TLD provides a solid foundation, it is not a magic bullet. Ultimately, your sending behavior, email content, and adherence to authentication standards like DMARC, SPF, and DKIM remain the most critical factors. Focus on building and maintaining a positive sender reputation through legitimate and consistent email practices. This comprehensive approach will ensure your emails consistently reach the inbox, regardless of the TLD.
Views from the trenches
Best practices
Always prioritize established TLDs like .com, .org, or .net for primary email sending to leverage their inherent trust and reputation.
Implement robust email authentication (SPF, DKIM, DMARC) regardless of your chosen TLD, as this is critical for verification.
Monitor your domain reputation regularly, using tools like Google Postmaster Tools, to detect any TLD-related issues early.
Maintain clean email lists and send relevant, engaging content to foster positive recipient engagement and avoid spam complaints.
Common pitfalls
Using very new or inexpensive TLDs (e.g., .xyz, .top, .biz) that have a high correlation with spam activities, leading to increased filtering.
Assuming that a clean web presence on a specific TLD automatically translates to good email deliverability for that same TLD.
Ignoring TLD-specific spam statistics or advisories from reputation-monitoring organizations.
Failing to adapt sending strategies when a previously acceptable TLD becomes associated with increased spam activity.
Expert tips
For cold email campaigns, consider using a distinct domain with a highly reputable TLD to protect your primary business domain's reputation.
Regularly check your domain against common blacklists and blocklists, which may list TLDs or domains within them that are known for spam.
If using a ccTLD, research its specific reputation within that country's email ecosystem, as practices can vary.
Consider the target audience and their familiarity with various TLDs, as unrecognized TLDs can sometimes reduce open rates due to perceived risk.
Expert view
Expert from Email Geeks says that generally, there isn't a significant difference in deliverability or spam rates between TLDs like .com, .biz, .net, .org, or .io, assuming a proper warmup. However, it's always good to check resources like Spamhaus reputation statistics, as mailbox providers might have internal rules for certain TLDs.
2024-04-08 - Email Geeks
Expert view
Expert from Email Geeks says that if a TLD correlates with spam, it will be used by spam filters. Cheap or unusual TLDs are often favored by spammers for throwaway domains, which makes sending legitimate mail from them a bad idea. While it used to be common advice to avoid new TLDs for email and stick to .com, this is less strictly true today, but some weight remains.
Cloudflare blog noted that TLDs like .uno, .sbs, and .beauty have had over 95% of their emails flagged as spam or malicious. This can lead to these TLDs being automatically sent to spam or having a significantly higher spam score. You can read more about TLDs and email phishing threats for further insights.
Gmail and 
Yahoo Mail. A .com or .org often carries more inherent trust for email purposes.
