Should I worry about test emails going to junk folders on irrelevant ISPs?
Matthew Whittaker
Co-founder & CTO, Suped
Published 1 Jun 2025
Updated 16 Aug 2025
7 min read
It’s a common scenario. You send out a test email, perhaps using an inbox placement tool, and suddenly you see that some of your messages are landing in junk folders. The immediate reaction is often panic, especially if previously everything went to the inbox.
However, if these junk placements are occurring on irrelevant Internet Service Providers (ISPs), particularly those outside your target audience (like German or Russian ISPs if your subscribers are primarily US-based), you likely don't need to worry too much.
While it's always good to be vigilant about deliverability, understanding the context of these test results is crucial. Not all junk folder placements are created equal, and some signals are far more critical than others.
The true meaning of test email results
Deliverability testing services use a vast network of seed mailboxes across many different ISPs and geographic locations. The purpose is to give you a broad overview of how your email performs globally.
However, an ISP in Germany will have different filtering algorithms, local spam laws, and user engagement patterns than an ISP in the United States. Your sender reputation with one ISP does not automatically translate identically to another, especially across different regions or languages.
If your primary audience is, for example, in the US, then the performance of your emails at major US ISPs (like Gmail and Outlook) is far more indicative of your overall deliverability health than isolated junk placements in non-target regions. These irrelevant ISPs often have no prior engagement history with your sending domain, making them more likely to classify test emails as spam, regardless of your actual sending practices.
Focus on your audience’s ISPs
Key Providers: Prioritize deliverability to major ISPs your target audience uses, such as Yahoo Mail, Gmail, and Outlook. These are the ones that truly impact your campaign success.
Engagement Signals: A good sender reputation is built on consistent positive engagement, which test emails to unknown ISPs lack.
Ignore irrelevant test results
Foreign ISPs: If your audience is not in Germany or Russia, test results from ISPs in those countries are largely irrelevant to your actual deliverability.
Isolated Incidents: A few junk placements on obscure ISPs (or even private blacklists) shouldn't cause alarm if your performance on key ISPs is strong.
This doesn't mean you should completely disregard any junk placement, but rather, understand the context. As a Mailchimp user noted on Reddit, test emails going to spam are common and not always a sign of broader issues.
Focus on the relevant mailbox providers
Your focus should always be on the mailbox providers that host the majority of your actual subscribers. If your test emails consistently land in the junk folder for Gmail, Outlook, or Yahoo, then it's time to investigate. These are the critical indicators of your email deliverability performance. Learn more about how to determine if marketing emails are going to spam.
For US-focused senders, the behavior of these large providers dictates success. They use advanced reputation systems that factor in everything from sender authentication to user engagement and even historical spam complaints. A junk placement here indicates a real problem that needs addressing.
What about G Suite addresses? While these are B2B, and your primary focus might be B2C, their filtering often mirrors Gmail's consumer filtering. If you see consistent junking to G Suite addresses in your tests, it could be an early warning sign for your Gmail deliverability, even if your audience is B2C. It's an area worth keeping an eye on.
You can get insights from Google Postmaster Tools and other similar tools to gain visibility into your sender reputation with these major providers. These tools provide valuable data on spam rates, IP and domain reputation, and authentication errors, helping you focus your efforts where they matter most.
Factors influencing email placement
While irrelevant ISPs might not be your main concern, it’s still beneficial to understand the universal factors that often trigger spam filters. These apply across the board, regardless of the ISP, and knowing them can help improve your overall email health.
Common culprits include poor sender reputation (either your IP or domain), issues with email authentication protocols like SPF, DKIM, and DMARC, and low engagement rates from your recipients. Additionally, the content and structure of your email can significantly impact whether it bypasses or trips spam filters. As Omnisend explains, large files or too many attachments can also trigger filters.
It’s also important to remember that testing services use static seed lists, meaning these addresses never engage with your emails. Real recipient engagement, or lack thereof, is a huge factor. If your actual audience doesn't open or click, ISPs will eventually see your emails as unwanted, leading to junk folder placement. This is why it’s critical to understand how to tell if your emails are automatically going to spam for your real campaigns.
Common red flags for spam filters
Low sender reputation: A history of spam complaints, bounces, or low engagement can harm your domain and IP reputation.
Missing authentication: Lack of properly configured SPF, DKIM, and DMARC records makes your emails look suspicious.
Spammy content: Overuse of caps, excessive images, broken links, or suspicious phrasing can trigger filters.
High bounce rates: Sending to invalid or inactive addresses can quickly damage your reputation.
Steps to improve your email deliverability
To ensure your emails reliably reach the inbox, focus on fundamental best practices, regardless of test results on irrelevant ISPs. The core tenets of email deliverability remain constant.
First, always ensure your email authentication records are correctly set up. This includes SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting & Conformance). These protocols verify that your emails are legitimately from your domain, a crucial step for gaining trust with ISPs. Utilize a blocklist monitoring service to stay informed of any blacklisting affecting your IP or domain.
Second, consistently monitor your sender reputation. Tools like Google Postmaster Tools provide insights into your performance with Google's ecosystem. Also, maintain a clean and engaged email list. Removing inactive subscribers and invalid addresses reduces bounces and minimizes the risk of hitting spam traps, which can significantly damage your reputation and lead to blacklisting (or blocklisting) by major ISPs. Consider running an email deliverability test specifically for your key target ISPs.
Always prioritize monitoring deliverability to ISPs that host your core audience, as these are the ones that dictate your true inbox placement.
Implement and maintain SPF, DKIM, and DMARC records to authenticate your emails and build trust with mailbox providers.
Regularly clean your email list to remove inactive subscribers and hard bounces, minimizing the risk of hitting spam traps.
Focus on crafting engaging content that encourages opens and clicks, sending positive signals to ISPs.
Common pitfalls
Over-analyzing test email placements on obscure, irrelevant ISPs while neglecting performance on major providers like Gmail or Outlook.
Ignoring signs of declining engagement rates from your real subscribers, which is a stronger indicator of deliverability issues than some test results.
Failing to update or correct SPF, DKIM, or DMARC records, which can cause authentication failures and push emails to junk.
Sending emails with generic or spammy content that can trigger universal spam filters, even if your sender reputation is generally good.
Expert tips
If using an inbox placement tool, configure it to focus tests on your primary target ISPs.
Understand that test accounts lack engagement history, making them more prone to junking than actual active subscribers.
Continuously track your domain and IP reputation using tools like Google Postmaster Tools.
Don't let minor issues on irrelevant providers distract from critical deliverability metrics where it matters most.
Expert view
Expert from Email Geeks says that if test emails are not landing in mailboxes where you have any subscribers, there is generally no need to be concerned.
2023-02-16 - Email Geeks
Expert view
Expert from Email Geeks notes that deliverability success can vary between Gsuite and Gmail in theory, but in practice, they usually show similar results.
2023-02-16 - Email Geeks
Prioritizing your deliverability efforts
While it's natural to be concerned when test emails land in junk folders, it's essential to differentiate between relevant and irrelevant ISP feedback. If your target audience isn't using a particular ISP that shows junk placement, these isolated incidents are often not cause for major alarm.
Your focus should remain squarely on your key audience's primary mailbox providers, such as Gmail, Outlook, and Yahoo. Consistent junking on these platforms is a strong signal that you need to review your authentication, content, and list management practices. For any persistent issues, it's wise to review why your emails are going to spam and how to resolve it.
By concentrating your deliverability efforts on what truly matters to your audience, you can avoid unnecessary panic and ensure your messages consistently reach the right inboxes, driving better engagement and campaign results.
Gmail and 
Outlook) is far more indicative of your overall deliverability health than isolated junk placements in non-target regions. These irrelevant ISPs often have no prior engagement history with your sending domain, making them more likely to classify test emails as spam, regardless of your actual sending practices.
Yahoo Mail, Gmail, and Outlook. These are the ones that truly impact your campaign success.
