How to Send Cold Emails Without Getting Blocked (2025 Guide)

Are you worried that your cold emails might land in spam or get blocked by ESPs?

I know what you’re going through…

You spend time writing personalized cold emails, only to see poor results, not because your messaging is wrong, but because the emails never make it to the inbox!

The problem usually lies with how the emails are sent. 

Most email service providers (ESPs) have strict rules in place. If you don’t follow them, your account could get blocked.

But here’s the thing: it doesn’t have to be that way!

You can send thousands, even tens of thousands of cold emails, without getting blocked or being blacklisted by an ESP.

In this guide, I’ll walk you through:

• Why ESPs block cold emails
• How spam filters actually work
• How you can send cold emails without getting blocked

By the end, you’ll have a tried-and-tested strategy to ensure your cold emails reach the inbox every time you hit send!

10 Steps to Follow to Send Cold Email Without Getting Blocked

In this section, I’ve listed 10 steps you can (and should) follow to successfully send cold emails that land straight in your recipient’s inboxes:

• Set Up Domain Authentication (SPF, DKIM, and DMARC)
• Use a Dedicated Domain for Cold Emailing
• Choose a Reputable Cold Email Platform
• Warm Up Your New Email Accounts
• Build and Maintain a Clean Email List
• Personalize Every Email You Send
• Include an Unsubscribe Link
• Spam-Test Your Email Before Launching
• Monitor Cold Email Metrics Regularly
• Scale Gradually, Not All at Once

Let’s get into the details.

1. Set Up Domain Authentication (SPF, DKIM, and DMARC)

An authenticated domain is the first sign that you’re a legitimate sender of email communication and take email security seriously.

Without authentication, there’s a high chance that your ESP will block your emails right away.

Let me quickly walk you through the three records you need to set up:

• SPF
• DKIM
• DMARC:

If you want to learn how to set up these records, check out my detailed guide to email authentication!

2. Use a Dedicated Domain for Cold Emailing

Use a dedicated domain for cold emailing. If your main domain gets flagged due to high volume or non-compliant practices, recovering its sender reputation can be difficult. 

And that’s the last thing you want for your company’s primary domain!

So, you should never use your company’s main domain to send cold emails. 

Here’s what you can do to avoid this problem: get secondary domains like <tryyourbrand.co> or <getyourbrand.com> for cold outreach. 

Next, create email accounts from these domains, and that’s it!

Your primary domain stays safe if your cold emails are hit with spam complaints.

Pro tip: Pick domains that look like your brand; it’ll keep things familiar for prospects while protecting your primary domain’s reputation.

3. Choose a Reputable Cold Email Platform

Gmail and Outlook are great for sending outreach or marketing emails. But they’re not the best options when it comes to cold email outreach. 

So, you may want to consider using cold email services designed specifically for this purpose!

They offer advanced features like:

• Sequence automation 
• Intuitive and friendly interface
• Email warmup & deliverability features 
• Personalization at scale
• Unified inbox for identifying high-value conversations

 The best cold email platforms also help you find and verify email addresses, allowing you to build accurate, high-quality lists that keep bounce rates low. 

Pro Tip: Choose a cold email tool that supports automatic account rotation. If one account runs into issues or gets blocked, the others can keep your campaign running smoothly without interruption.

4. Warm Up Your New Email Accounts

New or inactive domains have a low sender reputation: since they’ve not been used to send or receive emails, ESPs don’t know if they can trust them.

That’s why email warmup is important. 

It’s the process of gradually sending emails to accounts with a high email reputation. It helps you win your ESP’s trust and maintain high email deliverability.

To warm up your account, you should start by sending 10-20 emails per day and gradually scale the volume over time. 

But if you want to skip the manual hassle (especially if you need to warm up more than one inbox), use email warmup tools to automate the entire process!

They’ll automatically send warmup emails to highly reputable B2B accounts and help you build a high sender reputation within 2-4 weeks.

5. Build and Maintain a Clean Email List

One thing I’ve learned the hard way is that scraping random contacts from the web simply does not work.

Not only do you end up with an email list that doesn’t align with your ICP, but your list might also contain unverified or invalid emails.

The result? 

You’re sending emails to invalid accounts, which will increase your bounce rate and decrease your email reputation. 

And before long, you’ll end up with cold emails that are blocked by your ESP. 

Thankfully, there’s one solution you can use that’ll take care of both these problems:

Use trusted B2B lead finder tools that verify email accounts in real time. They’ll help you filter prospects based on your ICP and deliver accurate email addresses rigorously verified through a multi-step process.

Trust me, don’t skip this step: a little investment in the short run will help you create high-value outreach campaigns in the long run.

6. Personalize Every Email You Send

If you’re sending generic cold emails like:

“Hello <Prospect Name>, 

Hope you’re doing well…” 

Your prospects will probably move on to the next email before even glancing at your offer.

Plus, when your cold emails get ignored, they do more than just hurt your campaign; they destroy your deliverability.

Generic emails = fewer opens = fewer replies

And as soon as your engagement dips, your email reputation is under threat!

So, don’t send generic emails – personalize every cold email based on your prospect’s:

• First name
• Company
• Job profile
• Pain point

Pro Tip: Start your cold email with a personalized icebreaker, such as a recent LinkedIn post they shared or a company update. It will 2x your chances of getting replies.

7. Include an Unsubscribe Link

Not every prospect to whom you’re sending a cold email will be in the market for your product or service.

And that’s okay! 

But here’s the problem: if too many people hit “spam” instead of just ignoring your emails, ESPs might start blocking all your messages.

Even worse? You could land on a blacklist for breaking privacy laws like CAN-SPAM or GDPR. Yikes.

Here’s a simple fix to both these problems: always include an unsubscribe link with your cold emails.

It’s a win-win:

• You stay compliant and face no legal headaches.
• Recipients can simply opt out instead of angrily marking you as spam.
• Your list stays healthy: only engaged contacts stick around.

Pro Tip: Include the unsubscribe link where people expect it (like your email footer). Make it easy to find, and they’ll use that, not the spam button.

8. Spam-Test Your Email Before Launching

One of the best ways to ensure that your cold emails won’t be blocked is to spam-test them before launching your campaign.

Spam tests evaluate three things: 

• Sender information, such as email authentication.
• The email content for spammy language.
• Links or images you’ve included.

Based on this, it helps you spot issues with language, links, and formatting, so you can resolve them before sending your cold email to thousands of prospects.

Pro Tip: Use services like MailTester or GlockApps to spam-test your emails for free.

9. Monitor Cold Email Metrics Regularly

Modern ESPs don’t block cold emails suddenly: they observe your email sending practices over time to see if you’re violating their guidelines. 

In other words, they use a combination of metrics to determine whether you’re a spammer or a legitimate sender.

So, the best thing to do is track your cold email metrics, just like your ESP would.

Let me show you the crucial metrics that you must monitor: 

• Spam complaints: Should be less than 0.1%.
• Bounce rate: Should be less than 0.3%.
• Open rate: 20-40% is the accepted industry average.
• Reply rate: Anything between 1% and 5% is good.
• Blacklist alerts: Even one alert, and your cold emails could be blocked.

If you notice a drop in any of the above metrics below the rates I’ve mentioned, pause your cold email campaign immediately and conduct an email deliverability audit.

Pro Tip: You can use Google or Outlook postmaster tools to track your email deliverability metrics. If you’re using a cold email software, you can also use their dashboard for tracking these metrics.

10. Scale Gradually, Not All at Once

ESPs don’t like sudden changes in email sending patterns. It tells them that something is wrong, and you’re either sending spam or malicious emails.

So, start small and scale your cold email campaign gradually:

• Set up secondary domains.
• Warm them up.
• Spam-test a sequence.
• Send it to 50 prospects.

Then, wait: monitor your email deliverability metrics.

If you don’t see any sudden spikes or drops, increase the sending volume and repeat the process.

When in doubt, refer to this email deliverability checklist, it’ll help you create a consistent strategy for your cold email campaigns. 

Best Practices to Avoid Getting Blocked When Sending Cold Emails

Now that I’ve walked you through a step-by-step process of sending cold emails without getting blocked, let me share some industry secrets I’ve learned:

• Use a Dedicated IP Address
• Avoid Spammy Language
• Don’t Include Images or Links
• Space Out Your Emails
• Add a Real Business Address
• Use a Sunset Policy

Let’s get into it!

1. Use a Dedicated IP Address

When you use a shared IP, your email reputation depends on others using the same IP. If they send spammy emails, your emails might also land in spam—even if you’re doing everything right. 

So, if they send spammy emails, your deliverability suffers too!

To ensure that this never happens to you, I suggest setting up a dedicated IP address.

It puts you in control, so your sending reputation depends solely on your email habits, not someone else’s mistakes!

2. Avoid Spammy Language

Using phrases like “Best deal!” or “BUY NOW!!!” is a fast track to the spam folder. ESPs are quick to flag emails that sound overly promotional or aggressive.

To stay safe, stick to these simple writing habits:

• Keep your tone natural and conversational
• Skip the ALL CAPS
• Use exclamation marks sparingly

Before sending, run your email through a spam checker. It takes two minutes and could save your entire campaign from getting buried in spam.

3. Don’t Include Images or Links

There’s a long history of spammers using images and links to hide malicious content. 

And since ESPs can’t scan certain images or open all links, they generally don’t trust emails containing either of these elements in the content. 

So, keep your cold emails text-only: you can always send images or links once you’ve built a relationship with your prospects. 

4. Space Out Your Emails

Don’t Send Too Many Emails at Once.

Even with a good sender reputation, blasting out emails in bulk can raise red flags with ESPs.

Instead, spread them out. If you need to send 100 cold emails in a week, try sending 20 per day over 5 days.

This keeps your sending pattern consistent and lowers the chances of landing in spam.

5. Add a Real Business Address

If you’re adding an unsubscribe link to your emails, do one step further: include a valid business address in the footer.

This will help you comply with legal requirements and build credibility with your prospects in one go!

6. Use a Sunset Policy

Not everyone will hit unsubscribe—even if they’re no longer interested. But when someone repeatedly ignores your emails for months, it sends a negative signal to email providers.

To protect your sender reputation, it’s better to remove contacts who haven’t engaged in 3 to 6 months.

Before doing that, send a quick check-in like:
“Would you still like to hear from me?”

If there’s no response, it’s time to focus on prospects who are more likely to engage.

Cold Email Deliverability Checklist

Through this blog, I’ve walked you through everything you need to send cold emails without getting blocked: 

• Domain authentication
• Clean email lists
• Thorough email warmup
• Personalized, spam-free emails
• Privacy-compliant sending practices

Stick to these rules, keep an eye on your cold email metrics, and watch your emails land in inboxes, not spam folders.

Send cold emails without getting blocked: FAQs

1. What is the best way to send cold emails?

The best way to send a cold email is to use a professional domain (like Google Workspace), warm up your account, and send personalized emails. You should also follow ESP guidelines on authentication and use a cold email service for high deliverability.

2. Is it legal to send cold emails?

Yes, but with rules! Cold emails are legal when you follow the rules, such as those outlined in CAN-SPAM (US), GDPR (EU), or CASL (Canada). One way to ensure compliance is to always include an unsubscribe link and your physical address to stay compliant.

3. Are cold emails considered spam?

ESPs may consider your cold emails spam if you send generic emails in bulk without adhering to privacy laws.
So, personalize each email, target the right people, and respect anti-spam laws. Legitimate outreach never feels like spam email!

4. What is the 30-30-50 rule for cold emails?

The 30-30-50 rule is a popular approach to cold emailing. It suggests a structure for cold emails that focuses:

• 30% on personalized openers
• 30% on a value-driven body
• 50% on a clear CTA

The goal is to balance engagement and action to boost opens, replies, and conversations.

5. How to send bulk cold emails from Google?

To send bulk cold emails from Google, you can use GMass. It allows you to create cold email sequences with limited personalization capabilities.

However, the ideal option is to connect a Google Workspace account with a cold email service to send bulk emails with personalization and high deliverability.