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5 hacks to keep your cold emails from landing in the spam folder

Vladislav Podolyako
Vladislav Podolyako
Reading time:10 m

Whatever the “10 Commandments of Email Marketing” sound like, the 11th should be Thou Shalt Not Annoy. Neither the recipient nor email algorithms will tolerate intrusion — those who disobey never get a response because their emails go straight to the spam folder.

We at Belkins encountered such cases too many times while working with our clients. With the lack of outbound knowledge and omitting basic security rules of bulk emailing, their letters flew directly into junk folders. Not only did it result in low outreach performance, but their domains were repeatedly banned by email service providers, which made them create new ones again and again — what a pitiful waste of time and budget.

So is there a way out, or is a spam issue inevitable for all companies doing cold emails? Let’s figure it out.

Why do my emails go to spam?

Your messages might land in the junk folder because they don’t comply with regulations, because they contain suspicious content, or because you send them too often. Here’s an example of an email that had no chance to go to the inbox:

Example of Spam Email

Let’s review the common reasons why this and other messages are considered spam.

Your emails go against anti-spam laws

In 2003, the Controlling the Assault of Non-Solicited Pornography and Marketing (CAN-SPAM) Act established national standards for sending commercial emails in the United States. Canada finalized its anti-spam legislation, CASL, in 2014. European countries adopted General Data Protection Regulations, GDPR, in 2016.

Getting your cold emailing compliant with GDPR, CASL, and CAN-SPAM can feel limiting at first. On the other hand, it’s good to know what you can and can’t do with your emails so that they land in your prospects’ inboxes. Here are 3 basic rules to comply with:

  • Reach out to your potential clients without misleading or false claims.
  • Email only people who gave you specific permission to do so.
  • Always leave a possibility to unsubscribe from your marketing campaigns.

Not only can breaking those rules send your emails to spam, but also it can cost you money. For instance, Binance Australia had to pay a $2M fine for sending unsolicited emails that were nearly impossible to opt out from. 

Email service providers filter out spam content

To create business email addresses, marketers and salespeople use email service providers (ESPs), such as Gmail, Outlook, Yahoo!, McAfee, etc. These mailbox providers also protect users from malware, phishing, and spam by blocking suspicious content and behaviors. To do so, ESPs analyze multiple criteria, like subject lines, content, user engagement, previous sending history, email list quality, etc. 

Also, mailbox providers have their own limits on messages per day. Here are some of them:

Email service provider

Daily sending limit

Optimal number of emails
















Amazon SES



Proton Mail






Exceeding those limits will also increase your chances of looking suspicious and ending up in a spam folder. That’s why it’s better to start small and gradually increase the number of recipients. Also, we recommend using no more than half of the limit when your mailbox is new to leave some room for replies to emails.

Recipients mark emails as spam 

There might be different reasons why users send emails to junk, sometimes even without opening them. Of course, you can’t send 100% relevant and timely emails, but if the complaints exceed an average rate of 0.12%, it’s time to dig deeper into the problem.

Maybe you have a poor subject line, or it’s time to scrub your email list, or you’re sending emails too often. Not all of the issues are obvious and intuitive, and some of them are quite hard to identify.

Although the reasons listed above may give you hard times, they aren’t impossible to deal with. Check out how to prevent your messages from landing in a spam folder.

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How to stop emails from going to spam

To help you spot the problem on time and choose the best solution for it, we’ve prepared a number of tips. All of them are based on our experience of saving our own cold outreach, which resulted in creating an AI-based email platform, Folderly and offering email deliverability services to our existing and potential clients.

#1. Don’t send unsolicited emails

Before launching a cold outreach campaign, get explicit or implicit consent for marketing communication.

Explicit consent is the one where you ask your potential clients for permission to reach out to them. Usually, it’s an opt-in with disclaimer they should tick off when providing their personal data, like on a Salesforce form:

Example of the opt-in for marketing communications

You may also use a double opt-in by sending a confirmation email after your clients have subscribed to your updates. This helps you to ensure you add an existing and verified address to your mailing list.

Note: Double opt-ins are obligatory in some countries like Austria, Germany, Greece, Switzerland, Luxembourg, and Norway.

Implicit or implied consent is about indirect permission for communication when a person somehow expresses interest in your product or service. From our experience, even following your page on LinkedIn can be considered an implied consent. Yet, to comply with all regulations, we recommend that you stick with explicit permissions.

Also, you can take advantage of soft opt-ins. Soft opt-in means you can reach out to people who purchased something from you or shared their personal data before GDPR, CASL, or CAN-SPAM entered into force. Here are some other examples of recipients you can send emails to without additional authorization from them:  

Example of the opt-in for marketing communications

Source: Cold emailing compliant with GDPR, CASL, CAN-SPAM I Webinar by Belkins

Finally, and most importantly here, make it easy to opt out. Recipients should be able to unsubscribe at any time. You can either give them this option in the footer, as in the example from Notion below, or include a sentence like, “Let me know if you don’t want to get any messages from me” into your letter.

Example of Opt Out

Note: If you remove contacts from your mailing list manually, remember that under CAN-SPAM, you should respond to an opt-out request within 10 days.

#2. Build sender reputation

To avoid looking suspicious to ESPs, you need to have a sender score of 80 or more. This score depends on your mailbox sending history, open and reply rates, bounce rate, spam complaints, unsubscribe rate, and other metrics.

What can you do to gain trust of mail servers?

  1. Warm up your mailbox. If you’ve just registered an email account, start with sending small amounts of messages. Gradually increasing the numbers, you’ll let ESPs know your sending patterns, which define whether your emails will trigger spam filters or get to the recipients’ inboxes.
  2. Don’t exceed sending limits. As we’ve already mentioned, it’s better to leave some room for replies to your emails. For example, if the overall limit is 500 messages per day, use 200 for cold outreach, 200 for positive engagement (replies to your emails from your own accounts), and 100 to respond to the recipients who have answered your emails.

Belkins tip: Start warming up your mailboxes at least 2-3 weeks before sending a real-life cold campaign.

#3. Curate and segment your email lists

Mailing lists degrade by 22.5% yearly as people change jobs, and businesses change their ESPs or shut down. Thus, messages sent to nonexistent addresses just return to you. And as mentioned above, email bounce rate is one of the key factors that influence your sender score. To avoid losing your hard-earned reputation, it’s important to keep the bounce rate under 2%.

This is why you should regularly review your contacts database and remove outdated or invalid addresses from it. To validate emails you’ve got on your list, you can use such tools as Bounceless, ZeroBounce, NeverBounce, or any other. Also, don’t forget to exclude those who opted out from your mailings.

Finally, divide your lead lists into segments. This will allow you to deliver more tailored and relevant messages to each group and reduce the number of recipients labeling your emails as spam. Grab a few ideas for categorizing your potential clients:

By page visits

By funnel stage

By source

By origin

By demographics

Homepage visitors


Organic search

Webinar attendees


Product/service page visitors


Paid ads

Newsletter subscribers


Special offer page visitors

Repeat clients

Social media

Free materials downloaders


Note: Don’t buy a lead list as you risk getting unverified and noncompliant data.

#4. Personalize content to boost engagement

Around 73% of B2B clients strive for personalization

Crafting resonating messages is a win-win for you and your clients, as they decrease your chances of going to spam while matching your recipients’ needs. As a result, not only can you improve open and reply rates and nourish your sender reputation, but also you can skyrocket your sales. One of our clients, Born&Bred, reached 297% YoY growth and won 20 deals, thanks to highly tailored messages.

To prepare custom campaigns, do your research beforehand and then start with the subject line. Make it short and include the recipient’s or their colleague’s name in it if possible.

Example A: sync up with {{RecipientName}} at {{EventName}}

Example B: You or {{ReferralName}}?

Mention your contact’s name in the greeting and add relevant information about their company and pain points.

Hi {{RecipientName}},

I’m looking for the right person to discuss {{Company}}’s employee retention goals. Would it be you or {{Referral_Name}}?

With {{YourCompany}}, you can engage your employees to stay with {{RecipientCompany}} for longer and turn them into your brand advocates, which simplifies hiring top talent. For example, after implementing a custom partnership program, {{YourClient}} reduced their hiring costs by 37% and increased average employee life cycle from 1.5 to 4 years.

How about a quick call next week to discuss details of how {{YourCompany}} can help {{RecipientCompany}} optimize your HR budgets?

Kind regards,


#5. Avoid spam triggers in your content

Before sending your email templates, always check them for spam triggers, which aren’t usually tolerated by ESPs. Here’s an example of how an email from a reliable source was labeled as spam because of the implied urgency in the subject line:

Example of Spam Trigger in Subject Line

Find out the most common characteristics and examples of the no-go content:

  • Urgency: “Limited offer,” “Expires soon,” “Only a few seats left,” “Hurry up!” 
  • False or misleading claims: “Double your earnings,” “The information you requested,” “Good we do it!” 
  • Money talk: “Gain extra income,” “Earn more,” “Get $10M monthly”
  • Excessive punctuation: “Have you seen my email???” “I’m still waiting for your reply!!!”

If you’re not ready to review and double-check your content manually, you can use ready-made spam word checkers, which will highlight core issues in your sales cold email templates.

Also, ESPs can send your first-touch messages to junk folders if they contain attachments, or use HTML-heavy templates. 

Belkins tip: Better use plain text without images for cold emails.

Bonus piece of advice: Try to limit your sequences to 3 messages. Such length demonstrates the highest reply rate of 9.2%, which is 24% more than the industry average. At the same time, the fourth email in a row drops answers by 35%, and this decrease can negatively affect your sender reputation.

To sum it up, if you want your cold emails to avoid spam folders, you should regularly check your templates and mailboxes. We recommend doing spam testing before launching each new email marketing campaign.

Want to meet all the abovementioned criteria but find them difficult to cope with? Use specially designed automation platforms or hire an experienced cold outreach agency. Book a call with our experts to get smart email campaigns that always land in your clients’ inboxes and bring you regular opportunities.

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Vladislav Podolyako
Vladislav Podolyako
Co-founder and CEO of Belkins and Folderly
Vlad’s an expert in the areas of culture transformation and leadership development, B2B sales, and marketing. He spent more than 10 years building technology products, has a background in communication networks and electronic device engineering.