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Boost Email Deliverability with ESP Matching for Cold Outreach

Are your cold emails landing in the dreaded spam folder? If you’ve been watching your open rates drop or hearing crickets after launching a cold email campaign, there’s a good chance you’re missing a critical step: ESP matching.

Let’s break it down so you can start improving your email deliverability and getting better results from your outreach efforts.

What Is ESP Matching?

ESP stands for Email Service Provider. Think of Gmail, Outlook, Yahoo, and others. Each has its own rules when it comes to filtering emails. Some are pickier than others when deciding if an email is genuine or just more spam.

ESP matching is all about mimicking the email providers used by your leads. In other words, if most of your prospects use Gmail, you should send your cold outreach from a Gmail domain (or at least something that ESP will treat similarly). Doing this builds trust between your domain and your recipients’ email servers.

Why Does This Matter for Cold Emailing?

Cold emailing is tough. You’re reaching out to people who don’t know you (yet!). When your email service provider looks different or suspicious to theirs, it throws up red flags. Your email might:

  • Go straight to their spam folder
  • Get blocked entirely
  • Never reach the inbox at all

Matching your ESP to theirs increases the chances of your message getting delivered—and opened.

Think of It Like Speaking Their Language

Imagine walking into a small bakery in Paris and trying to order using only English. Sure, they might understand you, but there’s a good chance they’ll respond more warmly if you speak French.

ESP matching is similar. You’re “speaking the same language” as your recipient’s email provider. It helps you look more trustworthy and relevant in their system.

How to Match Your ESP with Your Leads’

Now that you understand why ESP matching matters, here’s how to put it into action.

1. Identify Your Leads’ ESPs

You might wonder, “How do I figure out what ESP my leads are using?” Great question!

Most business email addresses can be identified by their domain. For example:

  • Gmail: john.doe@gmail.com
  • Google Workspace: john@company.com (if hosted by Google)
  • Outlook or Office 365: hosted on Microsoft servers

There are tools out there—like Instantly’s ESP matching feature—that analyze your lead list and tell you which ESPs they use. It’s a huge time-saver and removes all the guesswork.

2. Set Up Matching Sending Accounts

Once you know what platforms your leads are using, create outreach domains that align with them. For example:

  • If 70% of your leads are using Google Workspace, your cold email account should also send from a domain hosted by Google (like G Suite).
  • If a chunk uses Outlook, consider having a few sending domains set up under Microsoft’s email services.

This takes time upfront, but it’s a smart investment for long-term deliverability.

3. Warm Up Your Email Accounts

Before you start blasting out emails from your fresh ESP-matched accounts, you need to warm them up. Otherwise, ESPs will see a new domain sending a sudden flood of cold emails and assume it’s spam.

Warming up means gradually increasing your sending volume over a few weeks. Again, tools like Instantly can automate this process for you.

4. Segment and Match at Scale

Handling one or two leads? You can do things manually. But for outreach at scale, you’ll need to segment your list smartly.

For example:

  • Create separate campaigns for Gmail leads vs. Outlook leads
  • Assign matched sending accounts to each group
  • Use automation tools to manage it all without pulling your hair out

This ensures every email you send is tailored for maximum deliverability.

Big Benefits of ESP Matching

So, what’s the payoff for all this work? It’s not just theory—you get real results.

Better Deliverability

Your emails are more likely to show up in the primary inbox, not promotions or spam. That alone can multiply your open rates.

Higher Engagement

If your email looks trustworthy and relevant, people are more likely to open it, read it, and respond.

Stronger Sender Reputation

When you do things the right way, ESPs begin to “trust” your domain. That reputation builds over time and pays off across all your campaigns.

Common ESP Matching Mistakes to Avoid

With all the benefits, it’s easy to mess this up in the excitement. Keep an eye out for these common mistakes:

  • Sending too much, too fast: Even with the right ESP, blasting thousands of emails out of a new domain is a bad look.
  • Using only one ESP: If your list includes leads from multiple providers (and it probably does), don’t ignore the rest.
  • Skipping warm-up: You’ll shoot yourself in the foot if you don’t take the time to build a solid sender reputation.

ESP Matching in Action: A Quick Example

Let’s say you run a SaaS company and you’re reaching out to HR managers across different industries.

You notice:

  • 60% of your leads are using Google Workspace
  • 30% are on Outlook/Office365
  • The rest are on smaller platforms or unknown domains

With this data in hand, you:

  1. Set up two separate cold email domains—one with Google, one with Microsoft
  2. Use your outreach tool to segment leads and assign the right ESP-matched domain
  3. Gradually warm up both domains before starting your campaign

The result? Your emails feel more “native” to the inbox, and your reply rates climb.

Final Thoughts: Is ESP Matching Worth It?

Absolutely. If you’ve already got great messaging and a solid lead list, but your cold emails still flop, ESP matching could be your secret weapon.

Even the best-written emails won’t make an impact if they never land in the inbox. ESP matching helps your messages get seen, giving you a better shot at building real connections.

So, whether you’re a sales pro, founder, or growth marketer, it’s time to get strategic. Audit your current setup, match your ESPs, and start sending with confidence.

Still feeling overwhelmed? Tools like Instantly make this process simple, automated, and scalable—even for teams handling thousands of emails a month.

Get Ahead with Better Email Deliverability

Want to improve your cold outreach results? Start with ESP matching today. It’s one of the easiest and most impactful ways to boost deliverability—and it doesn’t require a massive shift in strategy.

Got questions? Want help setting up the right ESP domains? Drop us a message—let’s get your emails back in the inbox where they belong.

Email smarter. Match better. Win more.