What TLDs should be avoided for email domains due to spam or reputation issues?
Matthew Whittaker
Co-founder & CTO, Suped
Published 6 Aug 2025
Updated 16 Aug 2025
8 min read
When choosing a domain name for your email, the top-level domain (TLD) you select plays a significant role in your email deliverability and sender reputation. It's not just about branding, it's about whether your emails reach the inbox or end up in the spam folder. Certain TLDs carry a higher risk of being flagged as suspicious by spam filters and internet service providers (ISPs).
The reason for this scrutiny is that some TLDs, especially newer or less regulated ones, are disproportionately used by spammers, phishers, and malicious actors. This rampant abuse leads to a tarnished collective reputation for the entire TLD, making it harder for legitimate senders to achieve good inbox placement. It's similar to living in a neighborhood with a bad reputation, even if your house is well-maintained.
So, how do you navigate this landscape? I'll explain which TLDs are generally best to avoid, which ones are safer bets, and how to maintain a strong sending reputation regardless of your domain extension choice.
How TLD choice influences email deliverability
The perception of a TLD can significantly influence how receiving mail servers assess your emails. Even before evaluating your specific domain's sending history, the TLD itself can trigger initial reputation checks. If a TLD is known for a high volume of spam or malicious activity, emails from domains using that TLD are more likely to face heightened scrutiny, be routed to spam folders, or even be outright rejected.
This impact on email deliverability is often tied to what's known as the TLD's shared reputation. Mailbox providers and anti-spam organizations track the overall quality of traffic originating from different TLDs. A higher percentage of abusive domains within a specific TLD can lead to its inclusion on internal blocklists (or blacklists) or result in higher spam scoring across the board for all domains under that extension. This means even a perfectly legitimate business could struggle if it chooses a TLD with a poor reputation.
Understanding this dynamic is crucial for anyone sending emails, especially for marketing or transactional purposes. While individual domain reputation plays a primary role, the foundational reputation of the TLD provides a baseline. Some TLDs simply start with a disadvantage, making the path to optimal inbox placement more challenging. For more on this, you can learn about how top-level domains impact email deliverability.
The TLD factor
Initial perception: Mail servers perform an initial assessment of a sender's TLD before delving into specific domain history.
Shared reputation: If a TLD has a history of high spam rates, it can negatively impact all domains within it.
TLDs to approach with caution
Based on industry observations and spam trends, several TLDs consistently appear on blocklists (and blacklists) or are associated with a higher likelihood of email filtering. These often fall into categories of less common domain extensions or those that are free or very cheap to register, attracting malicious users. Some key ones to be wary of include:
New generic TLDs (gTLDs): Extensions like .xyz, .top, .club, .buzz, .online, and .tech. Many of these were introduced post-2014 and have been observed to have a very high percentage of spam and malicious emails, some even over 95%, as reported by Cloudflare. This is why I advise against using these for email sending.
Freenom TLDs: These include .tk, .ml, .ga, .cf, and .gq. These TLDs were historically offered for free, making them attractive to spammers and leading to a highly negative reputation among many email networks.
Specific gTLDs with high abuse rates: Some other TLDs, like .cam, have been widely reported as cesspools of spam. If you're considering a more niche TLD, it's essential to research its reputation first. Spamhaus's most abused TLDs list is a valuable resource for this type of research.
.us TLD: While a country-code TLD, .us has also been singled out in some discussions as a TLD to avoid for email due to a higher association with spam. For specific advice on this, you can look into whether to block .us TLD for email signups.
The common thread among these TLDs is their frequent use in spam and phishing campaigns, leading to aggressive filtering by mailbox providers. While some legitimate entities might use these, the uphill battle for deliverability often outweighs any perceived benefits.
Common and reliable TLDs for email
For the highest chance of email deliverability, established TLDs that have a long history of legitimate use and robust governance are generally the safest choice. These TLDs benefit from a strong, built-in reputation of trust among ISPs and mailbox providers.
The undisputed champion for email sending remains .com. It is universally recognized and trusted. Other reliable options include .net, and .org. While .org has seen some discussion regarding registrar compliance issues, its overall reputation for email delivery remains strong for non-profit and community-based organizations. Additionally, .io and .co are increasingly common, particularly among startups, and generally perform reliably despite some filters assigning them higher spam scores than .com domains.
While even these reputable TLDs can be associated with spam if the sending practices are poor, their baseline reputation offers a significant advantage. Sticking with these widely accepted extensions is a fundamental best practice for boosting deliverability and ensuring your emails are perceived as trustworthy from the start.
TLD
Common Use Cases
Reputation for Email
.com
Commercial businesses, general use
Highest trust and reliability
.net
Network services, technology
Very reliable, good alternative
.org
Non-profits, community organizations
Generally good, but some registrar issues can occur
.io
Tech startups, increasingly popular
Reliable for many, but can attract higher spam scores than .com
.co
Companies, corporations, startups
Good standing, often used as an alternative to .com
Monitoring and maintaining your TLD's reputation
Choosing the right TLD is an important first step, but it's only one piece of the email deliverability puzzle. Even with a highly reputable TLD, poor sending practices can quickly tank your domain's reputation and lead to blocklisting. To ensure your emails consistently reach the inbox, I highly recommend a comprehensive approach to email security and deliverability.
One fundamental aspect is proper email authentication. Implementing SPF, DKIM, and DMARC records helps mailbox providers verify that your emails are legitimate and haven't been tampered with. This significantly reduces the chances of your emails being flagged as spam or phishing attempts.
Furthermore, consistent monitoring of your domain reputation across various platforms, including Google Postmaster Tools, is paramount. Regularly checking for blocklist (or blacklist) presence can alert you to issues before they severely impact your deliverability. Maintaining a clean email list, avoiding spammy content, and warming up new domains properly are also crucial steps. You can read more about why emails go to spam and how to fix it.
Views from the trenches
Best practices
Always prioritize established TLDs like .com, .net, or .org for core email communications.
Actively monitor your domain's reputation with tools like Google Postmaster Tools.
Implement strong email authentication: SPF, DKIM, and DMARC.
Segment your email sending by purpose and use dedicated subdomains where appropriate.
Common pitfalls
Using new or free TLDs (e.g., .xyz, .top, Freenom domains) for primary sending.
Failing to monitor blocklists (or blacklists) and address listings promptly.
Ignoring email authentication, which leaves your domain vulnerable to abuse.
Sending cold emails or high-volume campaigns from your main brand domain.
Expert tips
Consider a less common TLD for non-critical email or testing, but never for main brand communication.
Regularly audit your email list for unengaged subscribers and remove them.
Pay attention to spam complaints, as they are a strong signal to mailbox providers.
If you must use a less common TLD, ensure all other deliverability factors are perfectly optimized.
Marketer view
Marketer from Email Geeks says that the vast majority of .io emails received are spam, although some legitimate organizations use them, leading to a hefty score in filters rather than outright blocking.
2022-07-13 - Email Geeks
Marketer view
Marketer from Email Geeks says that startups using TLDs other than .com often face an uphill battle in terms of reputation, making it a harder sell to reputation systems.
2022-07-13 - Email Geeks
Final thoughts on TLDs and email deliverability
The TLD you choose for your email domain is more than just an aesthetic decision; it's a critical factor in your email deliverability. While it's possible to achieve good deliverability with a less common TLD, you're often starting with a disadvantage against spam filters that are predisposed to scrutinize or blocklist (or blacklist) certain extensions known for abuse.
My advice is to stick with the tried and true: .com, .net, and .org. If those aren't available, .io and .co are generally acceptable, but always be aware of their potentially higher spam scoring tendencies. Avoiding TLDs known for high spam rates is a simple yet powerful step to improve your overall email deliverability.
Remember, a strong domain reputation is built on a combination of factors: a good TLD, proper authentication, consistent sending practices, and diligent monitoring. By taking these steps, you can significantly increase the likelihood that your important messages land where they belong: in the inbox.
Spamhaus's most abused TLDs list is a valuable resource for this type of research.
