As a salesperson who is doing cold email outreach, what keeps you up at night? For most, it’s spam filters.
Those pesky little gatekeepers decide who gets to land in the inbox and who gets relegated to obscurity. It does not matter how personalized and thoughtful your email is or how helpful your offer is. If it gets filtered into spam, you have lost the war before a single bullet was fired.
As automation and email marketing increase in popularity, spam filters have also increased in sophistication. And they need to. By certain estimates, over 70% of all email traffic is spam.
Aided by AI and machine learning technology, spam filters today are increasingly stringent when it comes to determining what gets to the inbox and what gets filtered out. But in this crossfire between the spammers and spam filters, your thoughtful and relevant sales email can often end up as collateral damage. So, how should you as a salesperson or a marketer adapt? What can you do? First, embrace reality. Accept that spam filters make the inbox a better place. Make the spam filters your friend. In this article, we discuss the 16 critical things you must do to stay on the right side of spam filters.
- What Is Spam?
- How do Email Spam Filters Work?
- 16 Critical Steps to Avoid Email Spam Filters
- Build your Domain Reputation
- Set up your Email Infrastructure
- Monitor your IP Reputation
- Target the Right Prospects
- Monitor your Recipient Engagement
- Review and Minimize Bounces
- Make it Easy to Opt-out
- Follow Spam Law Guidelines
- Personalize your Emails
- Do not Follow-up Aggressively
- Use Automation Carefully
- Avoid Spam Trigger Words
- Use Different Templates
- Use open tracking sparingly
- Send attachments sparingly
- Focus on the Image-to-Text ratio
What Is Spam?
Any irrelevant or inappropriate emails that were sent in bulk to contacts who haven’t been researched or qualified ahead of time can be considered spam. Spam emails are often generic, impersonal, and templated. They rarely provide any real value or present information in a way that addresses the recipient’s needs.
Such emails often end up in the junk folder of your email service provider.
How do Email Spam Filters Work?
Email Service Providers (ESP) like Gmail, Outlook, Yahoo, etc, place filters in their systems in an effort to protect their users from unnecessary emails.
These filters, also known as Email Spam Filters, are algorithms that review incoming mail to prevent junk from reaching a user’s inbox. They use a rating system to judge if a mail is worth delivering to the inbox.
Spam filters weigh several parameters:
- Sender reputation,
- The volume of emails sent,
- Email engagement rate, etc –
And it assigns a spam score. Based on this they decide whether to pass an email through the filter and land it in the inbox. Since there are different approaches to catching spam and each filter has unique criteria to judge an email, it can get difficult to avoid spam filters. Not to worry, we’ve put together a few best practices you can follow to avoid spam filters.
16 Critical Steps to Avoid Email Spam Filters
There are a lot of steps in creating an email campaign that can avoid spam filters. From doing back-end activities like establishing to email service providers that you’re a legitimate sender to changing the way you write your sales emails. While your current focus is to avoid spam filters, your larger goals for running the campaign should be improving email deliverability and open rates. And doing the following activities will secure both.
So, we’ve segmented the actions into two sections:
Part 1. Things to do before you start email campaigns
Part 2. Things to do when writing your email content
Part 1. Things to do before you start email campaigns:
Just like how Rome wasn’t built in a day, you shouldn’t start sending your email campaigns from day 1. You have to set things in motion for your domain and email in order to start sending cold emails at scale and get higher open rates. Otherwise, the sudden and large volume of activity with your email account signals the ESP of suspicious activity and therefore your email address stands the chance of ending up on the blacklist. So, here are the different things-to-dos that can help you avoid email spam filters.
1. Build your Domain Reputation
The first step to avoiding email spam filters is to appear as a legitimate sender.
Spam filters bank on your Domain Reputation to evaluate your reliability – to determine the positioning of your email between the inbox and spam folder – so it’s pivotal to maintain it properly.
Your domain reputation is evaluated based on the following factors:
- Spam rate: The percentage of emails sent from a particular domain that were filtered out and landed in the spam folder directly.
- Bounce rate: This refers to the percentage of emails sent from a domain that was rejected by the prospect’s email server and returned to the sender.
- Spam report: If a prospect particularly marks you as spam, it is considered as a spam report. Spam reports are the last thing you’d want as an email sender – they immediately set off spam filters and severely affect your email deliverability. Regularly tracking these metrics and keeping them minimal is the best way to build your domain reputation.
Apart from these, it’s also important to have a method to protect your emails from spoofing but surprisingly, only a few companies have implemented it. One of the methods that you could implement easily is Domain-based Message Authentication, Reporting and Conformance.
2. Set up your Email Infrastructure
Another important step to avoid email spam filters is to set up your email infrastructure properly. This simply means that you have to authenticate the domain that you will be using to send the emails.
Domain Authentication is a technical standard that allows the email recipient’s server to confirm your identity – to verify that it’s really you who’s sending the email. This significantly reduces your chances of being marked as spam.
So, how do you authenticate your domain? Authenticating your domain involves setting up three protocols –
a. Sender Policy Framework (SPF): This standard validates your identity by checking if your mail is sent from an authorized IP address of a particular domain.
b. Domain Keys Identified Mail (DKIM): This authentication protocol affixes a digital signature to every outgoing email from a particular domain name, which is then verified by the prospect’s system. Meeting this standard ensures that an email is not tampered with during its transmission.

c. Domain-based Message Authentication, Reporting, and Conformance (DMARC): DMARC policies verify if the sender’s domain is authenticated with SPF and DKIM protocols and provides information on what to be done in case the sender is not verified (such as sending to the spam folder, rejecting the mail, etc). Contact your IT team to check if your SPF and DKIM are set properly.
3. Monitor your IP Reputation
An IP address is a number registered in your domain that is authorized to send emails/messages on behalf of the domain. Use a reliable IP address to send emails.
Every IP address has a rating and if it is low your emails will likely be considered spam and might be at risk of not being delivered. That is why it’s crucial to maintain a good IP reputation. Use tools like Sender Score by Validity or Barracuda Central to check if your domain or IP’s reputation is moving up or down over a period of time. If you see your reputation going downhill, it might be time to cut the volume down.
4. Target the Right Prospects
Only contact prospects who have a real need for your product and are likely to benefit from your services. This will improve the chances of your prospects replying to your emails and will boost your engagement rate. The best way to go about targeting the right prospects is to first build an Ideal Customer Profile (ICP) for your product/service.
Here’s a complete guide on building your Ideal Customer Profile (ICP).
5. Monitor your Recipient Engagement
Email spam filters constantly monitor how prospects are engaging with your emails. Engagement metrics like reply rate, click rate, etc indicate spam filters about your prospects’ interest in receiving your emails.
When a prospect positively engages with your mail by replying to it or adding you to their contacts, it sends a strong positive signal to the spam filters that you’re an emailer with credibility. This will in turn shoot up your sender’s reputation.
6. Review and Minimize Bounces
Tracking bounce rate helps you evaluate the risk of being blacklisted by spam filters.
An email is considered bounced when it is not delivered for permanent reasons such as fake email addresses or your prospect’s domain not being verified. This is something you’d want to avoid. The more bounces you get, the more your reputation suffers and the more difficult it is to avoid spam filters. It is a vicious cycle that is tough to get out of and your email deliverability will suffer for a long time.
Review your bounces regularly. The best way to minimize bounces? Keep your email list fresh, regularly cleaned, and verified from time to time. A “clean” email list has a bounce rate of less than 1%. Anything above that will alert the spam filters that you’re sending emails to stale email addresses. You can also take the help of email verification services like Klenty, or Hunter to validate your email addresses.
Part 2. Things to do while writing your emails:
So, when you’ve actually sat down to flex your writing muscles, what can you do to ensure your emails don’t end up in spam? We break down your options step-by-step:
7. Make it Easy to Opt-out
One easy way to reduce the likelihood of being reported as spam is to make it easy for your prospects to unsubscribe.
Provide unsubscribe links at the top or bottom of your emails, so that if your prospect is not interested in hearing from you, they can quickly and painlessly opt out – without having to mark you as spam. If your prospect chooses to opt-out, make it frictionless. Don’t ask them to re-enter their email address or username or pass additional hoops – it shows that you respect their preferences. Adding a compulsory opt-out isn’t just a deliverability factor, it’s also required by the cold emailing rules in different countries. Want a refresher on cold emailing rules? Check here.
8. Follow Spam Law Guidelines
Understanding and complying with the laws in the countries you’re prospecting into will limit the number of complaints against your domain, ensuring your emails land where you want them to – in the inbox. Make sure your emails comply with the standards set by the CAN-SPAM act such as:
- Provide a physical mailing address.
- Don’t use any deceptive subject lines.
- Honor opt-out requests promptly.
- Accurately identify the person you’re messaging.
9. Personalize your Emails
Personalization tells your prospects that you know who they are. It shows them that you’ve put some effort into messaging them. This makes your prospects receptive to your emails and increases the chances of engaging with them which will in turn improve your engagement metrics.
Want to read up on how to personalize your cold emails and follow-ups? Read our 9 techniques here.
10. Do not Follow-up Aggressively
No denying. Follow-up emails are extremely important to stay on top of your prospects’ minds. But if you’re aggressively following up with too many emails in a short span of time, you’re likely to irritate prospects and they might even end up reporting you spam – the last thing you’d want as a mail sender. Maintain a reasonable time gap between each of your follow-ups. Structure your cadence in such a way that your follow-ups provide value to your prospects while not being too frequent.
Pro Tip: On sending break-up emails in her sequences, Metadata’s top-performing SDR manager, Ashley Dees, told us in our SDR X Factor series that she doesn’t send them. She adds that prospects who did not respond to the sequences get added to a nurture sequence filled with useful bits of information that is helpful to the prospect, kind of like a newsletter. Give it a try and let us know if it works.
11. Use Automation Carefully
Spacing out the time period between individual emails – instead of blasting them all in one go – helps improve email deliverability. If you are using an outbound sales automation software (like Klenty) to send mail merges or cadences, set it up such that there is a reasonable interval between emails. For example, at Klenty, we use a random interval of approximately 2 minutes between each email sent by you. Sending 100 emails in a minute is a signal to the email service provider that you may be a bulk emailer.
Here’s how to improve your email deliverability.
12. Avoid Spam Trigger Words
If it sounds too good to be true, it’s probably spam. Words like ‘Free’, ‘Order Now’, ‘Make $$$’, or multiple exclamation points, strange formatting, and different colors are all big red flags. Unnecessary uppercase words, using any color other than black and blue, and one too many punctuations also convey that you’re desperately trying to get their attention, just like spammers.
In a snapshot, if your email is
- Manipulative,
- Cheap,
- Talks about fantasy land,
- Unethical,
They’re going to land in spam.
So, how do you know your emails don’t have such words? Put your email copy through a mail-tester to check if your template has spammy words that can decrease your chances of deliverability.

Here are 40 common spam words you should start avoiding. These words have been compiled from the internet:
- Symbols and numerical: 0%, 0% risk, 99%, #1, $$$, 100% free, 100% satisfied, 50% off, !!!!!,
- About Money & Promotions: Affordable deal, Amazing stuff, At no cost, Amazing offer, Avoid bankruptcy, Best price, Billion dollars, Bonus, Certified, Claim your discount, Deal, Explode your business, Free, Free access, Free bonus, Great deal, Congratulations.
- Exclusive offers: Limited time, Get it now, Once in a lifetime, For new customers only, Offer expires, Deal ending soon, You are a winner!
- Telling instead of showing: Use phrases like ‘The best, Fantastic without explaining why something is the best or fantastic.
13. Use Different Templates
Your recipients’ Email Service Providers are constantly tracking your email activity – if you repeatedly keep sending the same email copy, you might alert the spam filters.
Try experimenting with the different components of your email –
- The subject lines,
- The email body copy,
- The call-to-action,
- Or even the email signature..
A/B testing your subject lines, email copy, etc will help you understand what’s working in your cold email marketing campaign, and apply that to all your campaigns. With Klenty, you can set up multiple A/B testing options that will help you pick subject lines that record the most opens, email copies that push prospects to reply, and CTAs that drive action.
Useful Resource: Here is a collection of 120+ Cold Email Templates.
14. Use open tracking sparingly
It is recommended to limit the number of links added to your email copy as they tend to have a negative impact if your prospect has advanced spam filters. For the really sophisticated prospects, you may even want to turn off email open tracking as it could trigger their spam filters.
15. Send attachments sparingly
A lot of spammers are known for their spammy attachments, hence, there’s a high chance that email service could mark your email as spam if it notices heavy attachments.
That’s why attachments have a negative impact on deliverability. It would be a good idea to hold off on sending attachments unless you really need to. But we understand the need for attachments, in a bid to keep your cold emails short and sweet, we might need to send large bits of information via attachments. So, if it’s absolutely required then upload to a cloud-like Google or Dropbox and send the link over.
16. Focus on the Image-to-Text ratio
Spam filters block any email that doesn’t maintain a healthy balance of text and images. So, as a general guideline, it is recommended to maintain a ratio of 80% text to 20% images in your campaigns – if you have to use images. We know how important it is to break the pattern of your recipient’s email reading experience, an image that is relevant to their pain point or work would do wonders to your reply rates, but maintain the 80-20 rule when doing so.
It all boils down to this: Stay on the right side.
Take a look at your spam folder some time – you’ll know what a savior spam filter is actually. Without them, our inboxes will probably be full of emails from random strangers offering a fortune – if only we give them our banking passwords.
Spam filters do serve a great purpose. Life will indeed be harder without them. But given the sheer volume of emails they need to classify, they’re just not fair all the time. They do filter out important emails once in a while. The only way to consistently get past them is to always do the right thing.
Difficult? Maybe. But doable.
Target the right prospects. Comply with the spam law guidelines. Send personalized emails. Avoid spam trigger words. Craft a professional-looking mail. It’s all about getting the basics right. As long as you get
them right, you’re good to go. And we hope this article gets you there.
FAQ
Has Google banned email warm-up services?
Email warm-up services were effectively ended by Google’s crackdown on tools that provided the same by using the Gmail API. The news broke recently after a popular email warm-up tool sunsetted its warmup services because of a warning Google sent them over the tool’s usage of its API access. Does this impact you? No. Except that your email account will stop sending and receiving automatic emails as part of the warmup process. In short, you’ll have to do the warmup process yourself.
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