7 best practices to build a strong email infrastructure for cold email

Most people lose their cold email battle before they even write the email.

Not because their offer sucks.

Not because they can’t write good copy.

It’s because their email never makes it to the inbox.

Cold email works only if you show up.

And showing up means building the right email infrastructure, the system that makes sure your emails land in the primary inbox, not spam.

Here’s the problem:

• If you send from your main domain → you risk killing your brand’s reputation.
  
  
• If you skip SPF, DKIM, and DMARC → filters will block you without a warning.
  
  
• If you send too much, too fast → your domain burns out.
  

This guide is going to show you exactly how to fix that.

You’ll learn the best practices to:

• Protect your domain reputation
  
  
• Set up SPF, DKIM, and DMARC the right way
  
  
• Warm up your mailboxes so they can scale safely
  
  
• Monitor deliverability like a pro
  

If you skip this, you’ll keep wondering why your open rates are low, your replies are zero, and your “perfect” emails are being ignored.

Read on.

Your cold email deliverability depends on it.

What Is Email Infrastructure for Cold Email?

Email infrastructure for cold email is the technical setup that decides if your emails land in the inbox or spam.

It consists of:

• Domains → Separate addresses you send from, so you don’t risk burning your main website domain.
  
  
• Mailboxes → The actual email accounts connected to those domains.
  
  
• DNS Records (SPF, DKIM, DMARC) → The authentication stamps that prove you’re a real sender, not a spammer.
  
  
• IP Reputation → Your “trust score” with email providers, based on your sending history and engagement rates.
  

Cold email needs a completely different setup than your everyday Gmail or Outlook account.

Why?

Because Gmail and Outlook are built for personal or internal communication, not for sending hundreds or thousands of cold emails a month, push them too hard, and they’ll throttle or block you.

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Why Email Infrastructure Matters for Cold Email Deliverability?

Cold email deliverability is simple: if your setup is wrong, your emails never get seen.

How Poor Setup Triggers Spam Filters

Spam filters don’t care if your offer is amazing.

They check:

• Are your SPF, DKIM, and DMARC records correct?
  
  
• Is your sending domain trusted?
  
  
• Are you sending at a safe daily volume?
  

If the answer to any of those is “no,” your email gets flagged. 

Sometimes it lands in spam. Sometimes it’s blocked entirely before the recipient even sees it.

What Google & Outlook Look For?

Both Google and Outlook have strict rules:

• Consistent DNS authentication (SPF/DKIM/DMARC must match).
  
  
• Low bounce and spam complaint rates.
  
  
• Gradual sending volume growth (no sudden spikes).
  
  
• Positive engagement (opens, replies, clicks).

Outlook Alternatives for Cold Email Outreach

If you fail here, they'll start throttling your sends, even to people who want your email.

The Hidden Cost of Bad Infrastructure

When your infrastructure is weak:

• Your domain reputation tanks.
  
  
• Your domain can get blacklisted, sometimes permanently.
  
  
• Every lead you paid for is wasted because your email never landed.
  

It’s not just lost sales. It’s lost trust in the email providers, which can take months to fix.

But here Mailforge can help.

With Mailforge, deliverability isn’t an afterthought; it’s built in:

• Automated SPF, DKIM, and DMARC setup so every domain passes authentication.
  

• Safe sending limits per mailbox to prevent domain burnout.
  
  
• Shared IP pools tuned specifically for cold outreach.
  
  
• Free warm-up credits so new mailboxes can build a reputation before you scale.
  

Instead of guessing what Google and Outlook want, Mailforge sets it up exactly as they expect, out of the box.

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7 Best Practices to Build a Strong Email Infrastructure for Cold Outreach 

Let’s check in:

1. Use a Dedicated Sending Domain 

Your company’s main domain is your brand’s reputation. 

But if you’re doing it for cold outreach,  you’re likely to risk your brand domain's sending reputation, basically all emails from your own domain are likely to go to the spam folder.  

The best way to approach this is to buy a separate sending domain similar to your brand name for cold email. 

For example, if mailforge.ai is your brand domain, you can use domain names like heymailforge.com, teammailforge.com, usemailforge.com…etc

This isolates risk; if that domain’s reputation drops, your main site stays safe.

How many email accounts do you need per domain for cold outreach? 

A good rule is 1 domain for every 3–4 mailboxes you plan to run.

Mailforge makes it easy to add and configure multiple domains at once, so scaling isn’t a manual process.

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2. Set Up SPF, DKIM, and DMARC Records Correctly 

These three records are the foundation of your email’s trust and deliverability:

• SPF → Proves your mail server is allowed to send on your domain’s behalf.
  
  
• DKIM → Digitally signs your emails so providers know they weren’t altered.
  
  
• DMARC → Tells providers what to do if SPF/DKIM checks fail.
  
  

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The challenge with setting up SPF, DKIM, and DMARC is that it’s time-consuming — but still critical. 

Managing this for 1–2 domains is manageable, but at scale, it becomes a real headache. 

If you’re scaling your cold outreach, you can use Mailforge to purchase domains in bulk and automatically configure SPF, DKIM, and DMARC correctly.

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3. Create Multiple Mailboxes Per Domain

One mailbox sending too many cold emails daily is the fastest way to kill a domain.

Safe sending limit: 20-30 cold emails per mailbox per day. To scale outreach, add more mailboxes instead of cranking up send volume.

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4. Warm Up New Mailboxes Before Sending Campaigns

A new mailbox is like a brand-new phone number; if you spam too soon, it gets flagged.

Warm-up means sending a small, steady stream of real-looking emails until providers trust you. 

Typical warm-up time: 2–4 weeks before scaling to full volume.

Mailforge includes free warm-up credits, so every new mailbox builds a reputation before you start hitting prospects.

Or you can use Warmforge (Email warmup tool) for warming up your accounts.

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5. Monitor Domain & IP Reputation

Your sender reputation is like a credit score; drop too low, and your emails stop delivering.

You can track it with tools like Google Postmaster or built-in monitoring inside Mailforge. 

If reputation drops, pause sending from that domain, fix bounce/spam issues, and resume only when scores recover.

Mailforge alerts you before issues become deliverability disasters.

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6. Use Distributed Sending Infrastructure

Private IP → Full control, but needs high send volume to build and maintain a good reputation.

Shared IP → Lower volume senders share reputation, which can be good if managed properly.

For most cold outreach teams, a distributed shared IP pool is safer, as you blend into healthy sender traffic, which boosts inbox placement.

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7. Keep Lists Clean & Outreach Relevant

Bad lists = bounces, spam complaints, and destroyed deliverability. Always verify emails before sending.

Personalisation isn’t just about better replies; it reduces spam complaints because recipients feel the email is meant for them.

Mailforge integrates smoothly with Leadsforge.ai to pull verified, targeted contacts so you’re not wasting sends on bad data.

4 Common Mistakes That Kill Cold Email Deliverability

Here are some of the mistakes you must avoid: 

1. Using Your Main Domain for Outreach

Your main domain is your brand’s lifeline.

If you burn it through cold outreach, Google or Outlook can block it, and that block affects every email you send, including ones to clients and partners.

Always use a separate sending domain for cold email.

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2. Skipping SPF, DKIM, and DMARC Setup

Without these DNS records, email providers can’t verify you’re a legitimate sender.

That’s like showing up to an airport without an ID; you’re not getting through.

Set them up right the first time, or use Mailforge that configures them automatically.

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3. Sending Too Many Emails Too Soon

New domains and mailboxes need time to build trust.

If you go from zero to hundreds of cold emails overnight, spam filters see you as suspicious.

Warm up first, then scale gradually.

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4. Ignoring Bounce & Spam Complaint Rates

High bounce rates tell providers your list is bad.

High spam complaints tell them your emails are unwanted.

Both destroy your sender's reputation fast.

Track these numbers, and pause sending when they spike, before the damage becomes permanent.

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Conclusion

If your cold email infrastructure is weak, it doesn’t matter how good your copy or offer is; your emails will never get seen.

We’ve covered exactly what makes a strong setup:

• Use a dedicated sending domain to protect your brand.
  
  
• Set up SPF, DKIM, and DMARC correctly so providers trust you.
  
  
• Create multiple mailboxes per domain to scale safely.
  
  
• Warm up new mailboxes before campaigns.
  
  
• Monitor domain & IP reputation like your business depends on it — because it does.
  
  
• Use a distributed sending infrastructure for better inbox placement.
  
  
• Keep your lists clean and outreach relevant to avoid complaints.
  

Follow these best practices, and you’ll stop wondering why your open rates are low or why your “perfect” campaigns get ignored. You’ll start sending cold emails that actually land — and get replies.

If you’d rather skip the manual setup, Mailforge can do all of this for you in minutes.

It handles domain setup, mailbox creation, DNS authentication, warm-up, and monitoring — so you can focus on outreach instead of wrestling with deliverability issues.

👉 Get started with Mailforge today and build cold email infrastructure that gets your messages seen, not filtered.