Is Your Email Going Straight Into SPAM Folders?

Is your email going straight to spam?

Many online business owners and operators have no idea if their emails are hitting spam folders automatically, or if their emails are on multiple blacklists. What are the consequences?

The Key Parameters of an Email that determine its Deliverability

Before we even look at email blacklists, we have to know if our emails are correctly configured to prevent them being abused by spammers, and to make them verifiable to the whole email system as verifiable.

These parameters are set up on the back end of the mail system you use: GMAIL, Your Website Back-End (as we do for many clients) etc. Here are the key parameters and concerns:

  • DKIM
  • SPF
  • RDNS
  • Domain Suffiix
  • Domain Blacklists
  • eMail Subject Line
  • List Unsubscribe Header

We'll take you through each of these and explain their utility and then tell you how we set them up for our clients:


DomainKeys Identified Mail (DKIM) plays a crucial role in email deliverability. It allows an organization to take responsibility for a message in a way that can be validated by a recipient. DKIM reduces the likelihood of your emails being marked as spam, as it adds an encrypted signature to the header of your outbound email messages. When the recipient's server receives the message, it decodes the signature using the sender's public key, ensuring the email hasn't been tampered with during transmission.


The Sender Policy Framework (SPF) is a verification system designed to prevent sender address forgery. SPF works by publishing a record to your DNS server that lists which IP addresses are allowed to send email on behalf of your domain. This assists in preventing spammers from sending emails with spoofed email addresses from your domain, thereby improving your overall email deliverability.


Domain-based Message Authentication, Reporting, and Conformance (DMARC) is a protocol that uses SPF and DKIM to determine the authenticity of an email message. DMARC gives email domain owners the ability to protect their domain from unauthorized use, known as email spoofing. The need for DMARC is increasing due to the rise in email-based threats that often lead to phishing attacks, information breaches, and other security issues.

RDNS (Reverse DNS)

Reverse DNS (RDNS) lookup is a process to determine the hostname associated with a given IP address. It's essential in email communication as many spam filters verify the sender's RDNS to check if it matches the outgoing email server. If your server doesn't pass this check, your emails could end up in the recipient's spam folder, decreasing your email deliverability.

Domain Suffix

The domain suffix, or Top-Level Domain (TLD), is the last part of a domain name (like .com, .org, .edu). The domain suffix can impact email deliverability as some email filtering systems consider emails from certain TLDs as more likely to be spam. Therefore, choosing a reputable domain suffix is important for improving email deliverability.

Domain Blacklists

Domain Blacklists are lists of IP addresses or domains known to distribute spam. These are used by email servers to rate the reputation of incoming email. If your domain is on a blacklist, your emails may be marked as spam or even rejected. Therefore, avoiding practices that might get your domain blacklisted is essential for maintaining good email deliverability.

Subject Line

The subject line of an email is a key factor in email deliverability. Spam filters and recipient engagement are highly influenced by the subject line. If it contains spam trigger words or is misleading, the email may be filtered out as spam. Moreover, a compelling subject line increases the chances of the email being opened by the recipient.

Short URL

Using a Short URL in your emails can impact deliverability. Spam filters often scrutinize emails containing short URLs because spammers often use them to mask malicious links. Therefore, it's recommended to use full, clear URLs or to use a reputable URL shortening service to prevent negatively impacting your email deliverability.

List Unsubscribe Header

The List Unsubscribe Header is a piece of code in the header of an email that makes it easier for recipients to unsubscribe from your emails. Including it in your emails is not only a good practice from a user experience perspective, but it can also improve your

Testing Your Email

Before you can take any action, you have to test your email. There are many tools available for doing this, and some of them are free to use. LAtely we have used this one:

This very useful tool will give you a complete set of measurements as shown here (Click for full-sized, readable image):

MAilgenius Sydney Business Web Result

The results above are for our own key email addresses. Let's take a look in order of the things people want to know first:

Email Blacklists

Here are the key lists:

Spamhaus Block List (SBL)

The Spamhaus Block List (SBL) is widely considered one of the most influential email blacklists. It contains IP addresses that Spamhaus has identified as being involved in sending unsolicited bulk email. Being listed on the SBL can significantly impact email deliverability as many email service providers and Internet Service Providers (ISPs) use it to filter out potential spam.

Composite Blocking List (CBL)

The Composite Blocking List (CBL) is maintained by the Spamhaus Project. This list specifically includes IP addresses of systems that are infected with malware and are under the control of spammers or cybercriminals. If an IP address is listed here, it may be automatically rejected by servers checking this list.

SpamCop Blocking List (SCBL)

The SpamCop Blocking List (SCBL) is a DNSBL (Domain Name Server Blacklist) that includes IP addresses which have transmitted reported email to SpamCop users. These IP addresses are potential sources of spam. Being listed on the SCBL can cause your emails to be blocked or sent to the spam folder.

Barracuda Reputation Block List (BRBL)

The Barracuda Reputation Block List (BRBL) is a well-respected blacklist maintained by Barracuda Networks. Many server administrators use this list to protect their users from potential spam and malware threats. Being listed on the BRBL can cause your emails to be blocked or marked as spam.

SURBL (Spam URI Real-time Block Lists)

Unlike the others, the SURBL doesn't block IPs or domains but instead lists websites that have appeared in unsolicited messages. If your website is listed here, links to your site could cause emails to be flagged as spam.

URIBL (URI Blacklist)

Similar to SURBL, the URIBL is a list of domains that appear in spam emails. If your domain is listed on the URIBL, this could cause emails containing links to your site to be marked as spam, thus impacting your email deliverability.

Can I Get Off the Blacklists?

Getting Off the Spamhaus Block List (SBL)

To remove your IP from the Spamhaus Block List (SBL), you must first rectify the issue that led to the listing. After that, go to the Spamhaus Block List Removal Center and follow the provided steps. This generally involves confirming that you're authorized to make the request, and ensuring that the issue has been resolved. If Spamhaus verifies this, they will remove your IP from the list.

Getting Off the Composite Blocking List (CBL)

To get removed from the Composite Blocking List (CBL), go to the lookup/removal section on the CBL's website. Enter your IP address and follow the instructions provided. However, the CBL usually requires that the malware infection be cleaned up before removal. If the spamming activity resumes after delisting, the IP address will be listed again.

Getting Off the SpamCop Blocking List (SCBL)

To be delisted from the SpamCop Blocking List (SCBL), first, stop the spamming activity that resulted in the listing. Then, visit the SpamCop Blocking List section and follow the delisting procedure which includes filling out a delisting request form. If your request is accepted, your IP will be removed from the list.

Getting Off the Barracuda Reputation Block List (BRBL)

If your IP is listed on the Barracuda Reputation Block List (BRBL), you should first identify and resolve the issue causing the listing. Once this is done, you can submit a removal request via Barracuda's IP Removal Request form available on their website. The removal process might take some time, and successful delisting will only occur if Barracuda confirms the resolution of the issue.

Getting Off the SURBL (Spam URI Real-time Block Lists)

If your website is listed on the SURBL, you need to rectify any issues (such as removing all spammy or malicious content) before requesting removal. Once done, you can go to the SURBL's delisting page, enter your domain, and follow the instructions provided. Keep in mind that SURBL will only remove your domain if they confirm the issues have been addressed.

Getting Off the URIBL (URI Blacklist)

To be delisted from the URIBL, first fix any issues that led to your domain being listed. This could include removing spammy content, resolving any security issues, or following best email practices. Then visit the URIBL's website and follow their removal process. Typically, this involves entering your domain and following the instructions. URIBL will remove your domain from their list once they have confirmed the resolution of the issues.

This can be very time-consuming, so the best advice of course is DON'T SPAM!!! Now for the more technical aspects:

Setting Up DKIM, SPF, RDNS and DMARC

These parameters can be set up at the back-end of your website or email host, depending on the systems. But it is a bit technical and most people will feel uncomfortable with it - and rightly so. If you find that you have failed one of these in the test above, you should contact your website host and ask them to fix it.  We provide this service for our customers who host with us.

What about List-Unsubscribe? 

Enter your text here...When  you look at the test results I posted here for one of our emails, you will see that 'List-Unsubscribe' is the one point on which we failed , but it gave us only a one point deduction. 

We can't fix that ight now because 'List-Unsubscribe is a header item placed in the email header by your mail client and if it's not there,  you need an -add-on for the mail client. We know that Outlook and G-Mail have the facility, but on Thunderbird, we only have the possibility to respond to emails with an 'List-Unsubscribe' header. Here is what we see on Thunderbird Mailbox shen an incoming message has 'List-Unsubscribe' in it's header.:

List-unsubscribe button in Thunderbird

This is really useful because we can unsubscribe with just a click. 

The Top 50 eMail Subject Lines to Avoid

Using these headings may well have your email sent straight to the spam box:

1. "Guaranteed success"

This phrase is commonly associated with spammy sales pitches and is frequently flagged.

2. "Be your own boss"

Often used in work-from-home scams, this phrase is a common spam trigger.

3. "Dear Friend"

This generic salutation can cause an email to be marked as spam due to its impersonal nature.

4. "Free investment"

Such financial claims are often too good to be true and are thus flagged as spam.

5. "Cash bonus"

This phrase is associated with online gambling or other shady financial offers.

6. "Risk-free"

Risk-free claims are often associated with scams, so they are flagged by spam filters.

7. "Winner"

Without proper context, this can trigger spam filters due to its association with lottery scams.

8. "Credit card offers"

Used in many fraudulent scams, this phrase is frequently flagged as spam.

9. "Act now!"

High-pressure language like this can make your email appear spammy.

10. "Special promotion"

While not inherently spammy, this phrase is overused in spam emails, making it risky.

11. "Income from home"

This phrase is common in work-from-home scams and will likely trigger spam filters.

12. "Cancel at any time"

Although it's a legitimate phrase, its overuse in spam emails has made it risky.

13. "Check or money order"

Associated with many scams, this phrase can trigger spam filters.

14. "Congratulations"

Without proper context, this can appear spammy due to its association with scam emails.

15. "Confidentiality assured"

Often used in scams, this phrase can cause your email to be flagged as spam.

16. "Fantastic deal"

Such enthusiastic language can trigger spam filters due to its common usage in spam emails.

17. "Join millions"

This phrase is frequently used in mass marketing spam and can trigger spam filters.

18. "Promise you"

When used in subject lines, it can come off as a false claim and trigger spam filters.

19. "Free membership"

This is a common phrase in spam emails, so it's often flagged as spam.

20. "Save up to"

While common in legitimate marketing emails, its overuse in spam emails makes it risky.

21. "See for yourself"

This phrase can be seen as manipulative and is often used in spam emails.

22. "Get out of debt"

This phrase is commonly used in financial scams, causing it to be flagged as spam.

23. "Do it today"

This urgent call to action can make your email appear spammy.

24. "Get started now"

High-pressure language like this can trigger spam filters.

25. "Sign up free"

Overused in spam emails, this phrase can be risky to use.

26. "Order now"

High-pressure sales tactics are a common feature of spam emails.

27. "Buy direct"

Associated with many scams, this phrase can be flagged as spam.

28. "Best price"

While not inherently spammy, its overuse in spam emails makes it risky.

29. "Save $"

Too-good-to-be-true financial savings offers can trigger spam filters.

30. "Free quote"

Often used in spammy sales pitches, this phrase can be flagged as spam.

31. "Free trial"

Common in legitimate marketing emails, its overuse in spam emails makes it a risky choice.

32. "No cost"

Free offer claims like this one can make your email appear spammy.

33. "No fees"

This phrase is commonly used in financial scams, causing it to be flagged as spam.

34. "Lowest price"

Unsubstantiated claims like this can trigger spam filters.

35. "No catch"

This phrase can make your email seem suspicious, thus triggering spam filters.

36. "No gimmick"

Like "no catch," this phrase can make your email appear less trustworthy.

37. "Free hosting"

This offer is overused in spam emails and can be risky to use.

38. "Prize winnings"

Commonly associated with scams, this phrase can cause your email to be flagged as spam.

39. "Reverses aging"

Unsubstantiated health claims like this one can trigger spam filters.

40. "Hidden charges"

This phrase can make your email appear suspicious, thus triggering spam filters.

41. "Meet singles"

Associated with dating scams, this phrase can be flagged as spam.

42. "You're a Winner!"

This phrase is often used in lottery and sweepstakes scams and can be flagged as spam.

43. "Double your cash"

Financial claims that seem too good to be true often trigger spam filters.

44. "You've been selected"

Used in many phishing scams, this phrase can trigger spam filters.

45. "Billion dollars"

Exaggerated monetary claims like this are often associated with spam emails.

46. "Join millions of Australians"

This phrase is commonly used in mass marketing spam, thus it can trigger spam filters.

47. "Earn extra cash"

Common in work-from-home scams, this phrase will likely trigger spam filters.

48. "Expect to earn"

Income claims, especially without context, can appear spammy.

49. "Potential earnings"

Like "expect to earn," this phrase can be flagged as spam due to its use in financial scams.

50. "Big bucks"

Spam filters often flag such exaggerated financial claims.

Setting Up RDNS (Reverse DNS)

if you fail this test, (which is very important), you must ask your mail host to set it for you. Even if you are technically competent, in many systems you won't have the access required to do this.

Domain Suffixes

Domain suffixes, also known as top-level domains (TLDs), do not inherently contribute to an email being marked as spam. However, due to historical abuse or misuse, some TLDs have been associated with a higher percentage of spam or phishing emails. Here are some of them:

1. .xyz

While a legitimate TLD, it's often associated with spam or phishing due to its low cost and popularity among bad actors.

2. .work

.work domains are sometimes used in employment-related scams and spam emails.

3. .top

This TLD has been frequently used in spam campaigns due to its affordability.

4. .click

Due to the nature of its name, the .click TLD is often misused in spam or phishing campaigns.

5. .link

Like .click, the .link TLD is commonly associated with spam or phishing emails.

6. .country

Previously reported as one of the most abused TLDs, .country domains can be seen as suspicious.

7. .kim

Another TLD that has been previously reported as having a high percentage of bad sites.

8. .science

This TLD has been used in various scams and spam campaigns in the past.

9. .gq

This country-specific TLD (Equatorial Guinea) has been frequently misused by spammers.

10. .cf

.cf (Central African Republic) is another country-specific TLD that has been abused by spammers due to its free availability.

General Conclusions About Setting Up an Email for a Business

Setting up an email for a business involves several crucial steps, from choosing the right email hosting provider to setting up the appropriate email authentication protocols. It's important not to assume that these parameters are automatically set up for you by your email service provider, as it's often necessary to manually configure and verify these settings. Here are some general points to consider:

1. Professionalism

A professional email address typically uses your business's own domain (, not a generic one ( This gives your business a more professional appearance and can help build trust with your clients or customers.

2. Authentication Protocols

Ensure the email authentication protocols like SPF, DKIM, and DMARC are properly set up. These protocols authenticate your emails, reducing the chances of them being flagged as spam and increasing the likelihood they'll be delivered to your recipients' inboxes. Do not assume these are automatically set up - check your settings and configure them as needed.

3. Avoid Spammy Elements

When composing emails, avoid elements often associated with spam, such as certain phrases in the subject line or certain domain suffixes. Also, ensure your email list is clean and that you have recipients' permission to email them. This can help improve your sender reputation and deliverability rates.

4. Blacklists

Regularly check to ensure that your domain and IP aren't listed on any email blacklists. If they are, take immediate steps to get them removed and to address the underlying issues that caused the blacklisting.

5. Regular Maintenance

Email for business isn't a set-it-and-forget-it task. Regular maintenance, including monitoring delivery rates, bounce rates, and open rates, is important to keep your email communication effective and your domain reputation high.


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About the author 

Keith Rowley MBA BSc (Hons)

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