Imagine this: you’ve got a brilliant product or service that you know can transform lives, but there’s one problem—you need to tell people about it. Not just a handful of people, but thousands of potential prospects who could benefit from what you’re offering. This is where cold emailing becomes your superpower. Done right, it’s like having a direct line to your audience, sparking conversations, building connections, and driving results.

But let’s face it: sending cold emails isn’t just about hitting send. Scale it up to thousands—say, 10,000 emails—and it becomes a challenge of deliverability, strategy, and precision. Gmail, Outlook, and Yahoo cap you at 500 emails daily, while Google Workspace maxes out at 2,000. Clearly, conventional methods won’t cut it.

To send 10,000 cold emails at once without landing in spam (and also make money from it), you need two things: the right strategy and a powerful cold email tool like Smartlead. On top of that, you’ll need 68 secondary domains and 200 email accounts (3 email accounts per domain) to make it all work seamlessly.

In this article, we’ll take you step by step through:

• What you need to send 10,000 cold emails
• How to send 10,000 cold emails without compromising deliverability

Let’s dive in!

Things You Need to Do Before Sending 10000 Cold Emails

For this part, I am guessing you already have a primary domain and a few email addresses. 

Example: Our primary domain is Smartlead.ai. 

If you don’t have a primary domain yet, buy one before going to the next part. If you need high-performing domains and mailboxes that are pre-configured, then you can explore SmartSenders.

Sign Up on a Cold Email Tool - Smartlead 

If you're thinking how to send bulk cold emails, the first thing you need is a cold emailing software, such as Smartlead. Smartlead lets you add unlimited email accounts, email warm up, create cold email campaigns, set follow-ups, schedule bulk emails, etc.  We offer 14-day free trial to help you get started immediately.

One of our customers achieved as high as 19% positive reply rate with Smartlead.

Make a list of your needs and set a budget. Go through the features of a cold email tool and see if those align with your needs before buying a cold email tool. 

Not to beat our own drums, but Smartlead is the best cold email outreach partner in the market right now.  

Buy Secondary Domains & Create 200 Email Accounts

Secondary domains are additional domain names that a business or individual gets to complement their main domain. 

For example, our primary domain is smartlead.ai, but our secondary domains are 

• smartleadgrowth.info
• smartleadinfo.co
• smarterleaderemails.co

Secondary domains are vital in sending bulk cold emails for 2 reasons: 

• Firstly, they help divide the email-sending load, improving deliverability.
• Secondly, instead of using the primary domain and risking its reputation, you can use the secondary domains. This strategy will prevent potential blacklisting issues of the primary domain.

How many secondary domains do you need for 10,000 cold emails?

If you're thinking how to send 1000 cold emails or more, always split your bulk emails into batches—a max of 50 emails per address. 

Let’s get into a little math to find the answer to this question. 

You want to send 10,000 emails per day. If you can only send 50 emails per address, you will need 200 email addresses (simply 10,000 by 50) to send 10,000 emails.

Now, it’s recommended to create only 3 email addresses per secondary domain. 

So, divide 200 by 3. You need  66 to 67 secondary domains. We always recommend buying one or two extra domains. So, buy around 68 secondary domains to send 10,000 mails. 

Similarly, if you're wondering how to send 5000 cold emails, you will need 33 to 34 secondary domains and 100 email addresses.

To send 1000 cold emails, 6 to 7 secondary domains are enough with 20 email accounts.

Add Bulk Email Accounts to the Cold Email Tool

Once you’ve the secondary domains and the 200 email accounts, add them to your cold email tool.

If you’re using Smartlead, check out this article for technical assistance. 

Email Authentication - DKIM, SPF, DMARC, and MX Records

SPF- Sender Policy Framework 

DKIM - Domain Keys Identified Mail 

DMARC - Domain-based Message Authentication, Reporting & Conformance. 

MX Record - Mail Exchange record

These abbreviations often confuse the daylights out of SDRs, but that’s okay. You’re not alone. Here’s an article on DKIM, SPF, DMARC, and MX Records to help you with everything related to it. If you are buying through SmartSenders, you won't have to worry about setting these up manually.

Warm-Up 

Warming up email accounts is a must to see success with cold emails, especially when you’re using new domains and sending 10,000 messages.

Warm up your new email accounts for at least 2 weeks before launching the campaign. 

Here are resources to help you out with warm-ups:

• How to do email warm-up using Smartlead
• Benefits of Warm-Up 
• Warm-Up analytics
• How to do email warm-up manually

For 10,000 messages, use a cold email tool with an AI-based warm-up feature. 

How To Send 10000 Cold Emails At Once

Sending 10,000 cold emails is similar to sending 100 emails. The difference lies in the number of secondary domains, the lead list, and how you segment and schedule it. 

Take a look at the cold email checklist and practices before launching your outreach campaign. It will save you from many evident mistakes. 

Let’s dig in. 

Create a Lead List 

The easiest way to create a lead list is to get a cold email tool that comes with a contact list building feature. 

For instance, with Smartlead, you can opt for this feature (Listkit integration) and create a targeted lead list with just a few clicks on the Smartlead app itself. 

If you want to use a separate platform for creating an email list, you have the below options: 

• Databases
• Email finders and scrapers

A database is a storehouse of info about potential customers. The information includes industry, contact details, company size, locations, and performance metrics. Using various filters, you can search these databases for potential customers that align with your ICP. Apollo.io is one of the most popular B2B databases. Here’s an article on How to use Apollo to create an effective email list

An email finder or scrapper is a tool designed to retrieve email addresses publicly posted on the internet. Popular email scrappers are Clay, GetProspect, Skrapp.io, Hunter.io, etc.

Here are a few more resources to come up with a lead list:

• Untapped leads & Automation with Clay
• BuiltWith - Technology-Focused Intent

Note: Always verify the lists before launching campaigns. Use Usebouncer, Bulkemailchecker, and MillionVerifier to verify the contacts. 

Upload the Lead List in CSV Format

Organise the downloaded lead list on a Google sheet or Excel doc using various columns to segment it properly. 

Now, log in to the Smartlead app and click on the ‘Email Campaign' section from the navigation menu. 

On Smartlead, you can either upload the lead list as a CSV file or import it directly from your CRM. 

Map the CSV Columns

Next, connect each CSV column to the right dropdown option. If you have extra fields, like "Custom First Line," choose "Custom" in the dropdown. This way, you can include specific info not covered by the standard fields, making your data more personalised.

Afterwards, you will see a pop-up with a summary of the contact list, as shown below. 

This summary is extremely crucial for bulk email outreach. Go through it and see if anything needs your attention.

Write the Email Sequence 

Once you click “Save & Next”, you will go to the next step—sequences. 

This is where you write the email body, subject line, and set the follow-ups for your 10,000-leads cold email campaign. 

When writing the email body, check out the “spam checker” section on Smartlead. It will show the words or terms that are likely to alert spam filters. 

Go through the results and improve your email copy accordingly. 

Set Follow-Ups

Even though you’re sending 10,000 messages, it’s important to follow up to get the best results. 

Here’s how we follow up at Smartlead. 

Don’t set more than three follow-up emails. Keep a healthy interval between each follow-up email. 

Choose Sender Accounts

Once done creating the email sequence, choose the email accounts you want to send from. In this case, you need 200 email accounts for sending 10,000 messages. 

That’s it. You’ve launched a 10,000-leads campaign successfully. Now, sit back and check the analytics dashboard on your cold email tool. 

7 Practices To Send Cold Emails In Bulk Without Getting Blocked

Sending bulk cold emails can be a game-changer when done correctly, but it also comes with risks. If mishandled, email service providers (ESPs) may block your account or flag your messages as spam, damaging your deliverability. To ensure success, follow these seven proven practices:

1. Authenticate Your Domain (SPF, DKIM, and DMARC)

Email authentication builds trust with ESPs and protects against spoofing.

• SPF ensures only authorized servers can send emails on behalf of your domain.
• DKIM adds a digital signature to verify email integrity and authenticity.
• DMARC specifies how to handle emails failing SPF or DKIM checks and provides insights to optimize authentication policies.

Work with your domain administrator to add these records to your DNS settings. Proper authentication is non-negotiable for improving deliverability and maintaining a strong sender reputation.

2. Warm Up Your Email Accounts

Avoid jumping into bulk email campaigns with new email accounts. ESPs monitor sudden spikes in activity and penalize suspicious behavior.

• Start by sending 10–20 emails daily to trusted contacts who can engage with them.
• Gradually increase volume over 8–12 weeks, allowing time to build a positive sender reputation.

Warming up ensures your accounts are seen as trustworthy by ESPs.

3. Use a Custom Tracking Domain

Using a shared tracking domain can hurt your credibility if others misuse it. Instead:

• Set up a custom tracking domain linked to your sending domain.
• Add a CNAME record to your DNS settings and configure it in your email platform.

This ensures links in your emails appear authentic, protecting your reputation and boosting deliverability.

4. Include an Unsubscribe Link

Compliance with laws like CAN-SPAM and GDPR isn’t optional.

• A clear, accessible unsubscribe link prevents recipients from marking your emails as spam.
• Regularly remove unsubscribed contacts to keep your list clean and engaged.

Offering an easy opt-out option not only protects you legally but also improves your engagement metrics.

5. Personalize Your Emails

Generic, one-size-fits-all emails often lead to low engagement and spam complaints. Personalization is key:

• Segment your audience based on their needs and preferences.
• Use personalization tokens like first names, company names, or industry-specific details.

Thoughtful personalization resonates better with recipients, increasing open and reply rates.

6. Send Emails in Sequences

Instead of sending 10,000 emails in one go, use carefully timed sequences:

• Spread emails over several days or weeks to avoid sudden spikes in activity.
• Nurture prospects with multiple touchpoints, increasing your chances of conversion.

Sequences help you engage meaningfully while staying under ESP volume thresholds.

7. Stick to Daily Sending Limits

Every ESP has limits. For example:

• Gmail allows 500 emails/day for free accounts and 2,000 for Google Workspace.
• Office 365 permits up to 10,000 emails/day, with a per-minute limit of 30.

Plan your campaigns carefully to stay within these limits, avoiding flags for excessive activity.

Legal Regulations for Bulk Cold Emails

1. In the US: The CAN-SPAM Act

If you’re targeting prospects in the US, the CAN-SPAM Act sets clear rules for commercial emails, including both B2B and B2C campaigns. Violations can result in fines of up to $50,120 per email. To ensure compliance, follow these key requirements:

• Accurate Sender Information: Use correct details in your “from” and “reply-to” fields so recipients can easily identify the sender.
• Valid Postal Address: Include your business’s physical address in the email footer.
• Clear Opt-out Option: Make it easy for recipients to unsubscribe from future emails.
• Honest Subject Lines: Avoid misleading subject lines that don’t match the email content.
• Promptly Honor Opt-outs: Remove anyone who unsubscribes without delay.
• Responsibility for Third-party Vendors: If you outsource email campaigns, you’re still accountable for compliance.

2. In Europe and the UK: GDPR

The General Data Protection Regulation (GDPR) governs data privacy for EU citizens and impacts how you approach bulk cold emailing in the region. Non-compliance can result in steep penalties—up to €20 million or 4% of your global annual turnover. To send GDPR-compliant emails, keep these rules in mind:

• Legitimate interest: Ensure you have a valid reason to contact each prospect, such as relevance to their role or industry.
• Transparency: Be clear about how you obtained their contact information. If a prospect requests not to receive further emails, respect their request immediately.
• Opt-out option: Include a simple and visible way for recipients to unsubscribe.

In the UK, GDPR remains in effect as part of UK law under the UK GDPR, alongside the Data Protection Act (DPA) 2018.

If your prospects are outside these regions, research and adhere to local email and data privacy laws. By staying informed and following best practices, you can conduct bulk cold email campaigns ethically and legally while building trust with your prospects.

What are the risks of sending too many cold emails at once?

Sending too many cold emails at once can lead to several risks, including getting flagged for spam, damaging your sender's reputation, and experiencing higher bounce rates.

To mitigate these risks, adhere to cold email rules and best practices. Use email verification tools to ensure you're sending to valid addresses and avoid spam traps. Slowly ramp up your email volume to build credibility with email service providers. Personalize your emails to avoid generic and spammy content.

Additionally, monitor your email deliverability and engagement metrics continuously. Utilize cold email-sending services that offer advanced monitoring and compliance features to stay within safe gmail sending limits and other providers email sending limits as well as maintain a healthy sender reputation.

How do you integrate cold email outreach with other marketing strategies?

Integrating cold email outreach with other marketing strategies amplifies your overall efforts and creates a cohesive approach.

Start by aligning your cold email campaigns with your broader marketing goals and messaging. Use insights from your content marketing, social media, and paid advertising efforts to inform your email content and targeting.

For example, leverage blog posts and whitepapers as valuable resources in your emails. Coordinate your outreach timing with other campaigns, such as launching a new product alongside a targeted cold email blitz. Track and analyze data across all channels to understand how cold email outreach contributes to your overall marketing performance. Combining these efforts ensures a unified strategy that maximizes reach and effectiveness.

How do you measure the success of a cold email campaign?

Measuring the success of a cold email campaign involves tracking key performance indicators (KPIs) that reflect your campaign goals.

Common KPIs include open rates, click-through rates, response rates, and conversion rates. Utilize bulk email software with robust analytics to monitor these metrics in real time. Pay attention to the quality of responses and the engagement levels of different segments within your email list. A/B testing various elements of your emails, such as subject lines and calls to action, can provide insights into what resonates best with your audience.

Ultimately, the success of a cold email campaign is determined by how well it generates qualified leads and drives tangible business outcomes.

How can you avoid getting your cold emails marked as spam?

Avoiding the spam folder requires a combination of technical setup, content strategy, and adherence to cold email rules.

Ensure your domain and email server settings, such as SPF, DKIM, and DMARC, are correctly configured to establish sender authenticity. Use email verification tools to clean your list and remove invalid addresses.

Craft compelling and relevant subject lines that avoid spammy words or phrases. Personalize your emails to make them more engaging and less likely to be marked as spam. Implement proper opt-out mechanisms and respect unsubscribe requests promptly.

Monitoring your sender's reputation and staying compliant with anti-spam regulations are also vital steps in avoiding the spam folder. 

By leveraging these strategies and tools, you can effectively manage large-scale cold email campaigns, ensure high deliverability, personalize at scale, and integrate with other marketing tactics to drive successful outcomes from your cold email outreach efforts.

Final Thoughts

Sending 10,000 cold mails is no different than sending 100 messages. The practices remain the same. If anything that changes is the number of secondary domains and email accounts used for that particular campaign.

If you’re a beginner, I recommend starting small. It will help you understand cold emailing as a process and provide a chance to gain a better understanding of your target audience. 

For beginners, 10,000 might be an overwhelming volume. But, if you still want to give it a shot, go ahead.

Feel free to reach out to the Smartlead team on the Slack channel or the customer support team if you need any kind of assistance.