How to Make Sure Your Cold Emails Avoid Spam Filters and Actually Get Delivered

Cold email remains one of the most powerful tools in B2B sales. It lets you bypass gatekeepers, scale outreach effortlessly, and—when executed correctly—connect directly with decision-makers.

But here’s the catch: most cold email campaigns fail before they even get started.

In highly regulated markets like Germany and the UK, where strict privacy laws govern email outreach, getting into the inbox isn’t just important—it’s the foundation of a successful outbound strategy. If your emails land in spam, your entire campaign is dead on arrival.

Mastering email deliverability isn’t just about avoiding spam filters—it’s about engineering a system that ensures your messages consistently reach the right inboxes at scale.

Why Cold Emails Get Flagged as Spam (And Why Most Companies Never Fix It)

Spam filters don’t randomly decide which emails to block. They identify specific patterns linked to low-quality, unsolicited, or irrelevant messages.

If your emails aren’t reaching the inbox, chances are you’re making one (or more) of these critical mistakes:

• Poor sender reputation – Your domain has been flagged due to past bad practices.

• Misconfigured email infrastructure – Missing or incorrect SPF, DKIM, or DMARC settings.

• Spam-triggering content – Using words or formatting patterns that get flagged.

• Unnatural sending behavior – Sending too many emails too quickly without a proper warm-up.

• Low-quality contact lists – High bounce rates damage your domain’s reputation.

Most companies don’t fix these issues because they assume cold email is all about the message itself. In reality, success depends just as much on how and where you send.

The companies that dominate cold email treat deliverability as a strategic priority, not just a technical detail.

The Technical Foundation: Setting Up Your Emails for Maximum Deliverability

Before you even start crafting emails, you need to ensure your sending infrastructure is bulletproof. Otherwise, even the best-written emails will never be seen.

1. Use a Dedicated Sending Domain

Never send cold emails from your company’s primary domain (e.g., company.com). Instead, set up a dedicated domain (e.g., companymail.com or companyoutbound.com) specifically for outbound emails.

Why?

• Protects your main domain from spam penalties.

• Lets you monitor and optimize deliverability separately.

• Prevents blacklisting issues that could impact your entire company.

2. Authenticate Your Emails (SPF, DKIM, DMARC)

Email authentication tells inbox providers that your emails are legitimate. Without these settings, your messages are far more likely to be filtered as spam.

• SPF (Sender Policy Framework) – Confirms your domain is authorized to send emails.

• DKIM (DomainKeys Identified Mail) – Encrypts and verifies your emails for authenticity.

• DMARC (Domain-based Message Authentication, Reporting & Conformance) – Ensures SPF and DKIM are aligned and prevents spoofing.

If any of these are missing or misconfigured, email providers like Gmail and Outlook—especially in regions with strict spam laws—will block your messages.

3. Warm Up Your Domain Before Sending Cold Emails

Launching a new domain and blasting out hundreds of emails immediately is a surefire way to get flagged.

Instead, use a domain warming process to gradually build trust with email providers:

• Start small: Send only 10–20 emails per day in the first week.

• Slowly increase volume: Scale up by 10–20% per week over 4–6 weeks.

• Encourage engagement: Prioritize responses to show inbox providers your emails provide value.

Skipping this step damages your sender reputation before your campaign even takes off.

How to Write Cold Emails That Stay Out of Spam

Once your technical setup is solid, the next step is ensuring your email content doesn’t trigger spam filters.

1. Avoid Spam-Triggering Words and Formatting

Spam filters flag emails based on certain red flags. Avoid:

• “Free trial,” “Limited-time offer,” “Buy now,” “Make money fast”

• Excessive bolding, ALL CAPS, or too many exclamation marks!!!

Instead, keep your email natural and professional—like you’re writing to a colleague.

2. Personalization Increases Deliverability

Generic, mass emails look like spam. Personalized, targeted emails feel like real conversations.

• Use the recipient’s name.

• Reference their company or a recent event relevant to them.

• Make it clear the email was written specifically for them.

Bad Example (Likely to Be Flagged as Spam)

Subject: Increase Your Sales by 200%!

Hi,

I came across your business and wanted to reach out. Our tool helps companies make more money fast! Would you be open to a quick call?

Best,
[Your Name]

This email is vague, salesy, and screams “spam.”

Good Example (Inbox-Friendly, Feels Genuine)

Subject: Helping [Company Name] improve [specific goal]

Hi [First Name],

I saw that [Company] is expanding into [new market]. We recently helped [similar company] reduce acquisition costs by 28% using [specific method].

Worth a quick chat to see if this applies to you?

Best,
[Your Name]

This feels like a real, human email—something you’d actually want to read and respond to.

3. Keep Your Sending Behavior Natural

Even if your email content is perfect, sending too many emails too quickly will still get you flagged.

• Stick to 50-100 emails per day per inbox.

• Space out emails—don’t send them all at once.

• Follow up strategically (3-4 times max).

Inbox providers track sending patterns—if you blast 1,000 identical emails in an hour, expect to be flagged immediately.

The Cold Email Advantage: Control, Scale, and Precision

Most companies fail at cold email because they never make it past spam filters. But those who master deliverability own their outbound pipeline.

• They reach decision-makers when others get filtered out.

• They scale outreach predictably without legal risk.

• They drive high-value sales conversations on demand.

At the end of the day, cold email isn’t just about what you say—it’s about how you send it. The businesses that get this right don’t just avoid spam—they dominate outbound sales.

Need help executing at the highest level? We’ve built and optimized cold email campaigns that consistently generate high-value conversations. The right strategy changes everything. Let’s talk.