November 19, 2021

Avoiding Spam Folder | 15 Practical Tips & Tricks to Bypass the Spam Filters and Hit the Email Inbox

As a marketer, you might be familiar with spam email. And would have experienced your email campaigns landing in the spam folder of your recipient. So why do emails land up in the spam folder, and how to fix that. Before we go into details, let us first understand the basics of a spam email.

What is a SPAM Email?

Spam is unsolicited emails sent in bulk. In short, spam is an email sent to individuals who know nothing about the sender or have previously refused to receive an email from the sender. 

Interestingly, according to  ReturnPath’s research, 21% of all emails sent by genuine marketers end up in spam folders. This issue causes a huge frustration for us as a marketer, as that one small mistake can easily get our messages classified as spam. 


Hence now the question is…. How do email messages get classified as spam? 

  • Your IP address is/has been used for spam—Even if you never intended to send spam emails,still could get flagged if your IP address was used for spam in the past.
  • If you send your campaigns through an email marketing service provider (ESP), your email is delivered through their servers. The servers and IP addresses used in this case are shared by multiple customers. So, if one other customer sends spam, it could affect your deliverability negatively.
  • On the other hand, the content itself can determine whether the email will end up in the inbox or the spam folders if your content triggered the spam filters. 

What is Spam Filtering? 

Spam filters detect unwanted and spam emails and stops it from getting into email inboxes. Spam filters are being used to make sure that the recipient will not get spammed. 

How do spam filters work?

Spam filters use an algorithm which contains some rule that assigns a numerical score to the probability of the message being spam to determine if the email is flagged as spam and blocked from going further.

There are different types of spam filters that are commonly used to keep unwanted emails out of inboxes:

  • Content spam filters:  parse and scan the entire email content for spam keywords that are commonly used and found in spam emails. 
  • Header spam filters: check the email header information to examine suspicious IP addresses and determine if it’s coming from an illegitimate source. 
  • Blacklist spam filters: block emails that come from blacklisted IP addresses or low reputation IP addresses.
  • Rules-based spam filters: set customized rules designed by an organization to be applied on all incoming emails. 

And here are 15 Tips to Bypass the Spam Filters and Hit the Email Inbox

  1. Keep your email list clean
    • If your email list contains outdated addresses or unengaged subscribers, you’re probably not getting the expected delivery rates and open rates. When that happens, your messages are seen as less relevant, and that can play a role in whether you’re sent to spam or not.
  2. Craft engaging subject lines
    • 69% of email recipients choose to report messages as spam based on the email subject line alone, so create subject lines that are relevant, useful, and low on exclamation points
  3. Invest in a third party sender accreditation
    • Sender accreditation  is a process to get a certificate from a third party that guarantees the senders as genuine senders and not spammers. It is an additional assurance that signals ISPs to let your emails bypass spam filters, and reach the inboxes. Returnpath and Validity are two sender accreditation programs that email marketers can check out to get certified as a reputed sender.
  4. Encourage replies and use an active reply-to email address
    • No one replies to spam emails. People simply delete or mark such messages as spam. So if you are getting replies to your emails it’s a positive signal to the email providers that these are genuine emails. Hence it makes even more sense to put a friendly reply-to address instead of the
  5. Avoid email attachments
    • Emails should have a good balance of text to images and other information. Building emails that are all image and no text, all code, and little text, or that have some attachments embedded information can drag you down and create the appearance of spamminess.
  6. Monitor your IP reputation
    • A bad IP address reputation will most likely lead your emails to the spam folder. Hence, it becomes important to regularly monitor your server IP address reputation. Online tools like lets you check your reputation and find out if you’re blacklisted.
  7. Take off hard bounces emails from your list
    • Sender reputation is a function of bounce rates. Carefully manage your reputation to improve deliverability. Emails to inactive addresses over time are recorded by an ISP as a spam trap hit. Once you are notified of a bounce by your ISP, remember to delete that email address from your list.
  8. Take off unsubscriber from your list
    • Respect your unsubscribers by ensuring they have the option to unsubscribe when they want to. And stop sending them emails immediately.
  9. Use a familiar sender name
    • Send emails from email addresses containing personal names. People prefer to open emails with personal names in the front box.
  10. Choose a reliable ESP
    • Always go with a reliable Email Service Provider. The good reputation of ESPs depends on the good reputation of their clients. ESP clients delivering high-value content with high scores on their IP addresses improve the ESP’s trustworthiness.
  11. Avoid spam trigger words
    • Using spam trigger words can increase the possibility of being trapped in a spam filter and landing up in spam. When you’re creating an email, find ways to convey relevancy and value. Here is a list of Top Email Spam Trigger Words to Avoid in 2021
  12. Use standard font – type, color, and formatting
      • Email marketers must not use irregular font type or multiple font colors, font sizes or text formatting options within an email. At the same time the email text should be clearly visible without any ambiguity. Irregular formatting options in email could trigger spam filters and make the email susceptible to spam. Below is a real example of a typical spam email using irregular formatting and clearly suggesting What not to do while formatting your email:


  13. Test your emails before sending
    • Testing improves your chances of reaching subscribers’ inboxes. There are many high-quality spam content checkers like Mail Tester to test the spam score of your emails before you send them.
  14. Monitor your email KPIs 
    • The rule of thumb for an email marketer is to ‘Monitor Your Email KPIs’. Automating email campaigns makes life easier for marketers, but one should closely monitor the sending and the post-send performance metrics. Do a comparative analysis of your campaigns to find out sudden drops in the open rates or jumps in bounce rates. Any outlier in this could indicate that your emails might not be hitting the inbox and might be caught up in the spam.
  15. Keep abreast of spam filter, anti-spam & ISP best practices
    • Keep updating your knowledge of spam filtering technology, anti-spam law, and ISP practices. The laws are constantly evolving regarding technology as a whole. There are strict penalties for violation, and it does not apply to bulk email alone


Unfortunately, there is no exact formula or guarantee that your email will not end up in spam. By paying attention to technical issues and following these 15 tips to avoid all spam triggers, you are more likely to reach the inbox, preserve your credibility, sender reputation and protect your IP address and domain from getting blacklisted as a spammer. 

Please let me know if you have any thoughts on the comment section 🙂

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