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Email Infrastructure:

The Foundation of
Successful Cold Outreach

Whether you’re new to cold email or a seasoned pro, email infrastructure is something you always need.
Explore different infrastructure options and best practices:
What Is Email Infrastructure?

At its core, email infrastructure refers to the system that powers your ability to send emails.

It includes everything from the domains and mailboxes you use, to the DNS records that authenticate your messages, to the sending servers behind the scenes. For cold outreach, your infrastructure isn’t just about sending - it’s about deliverability. Properly configured and maintained infrastructure is what separates high-performing campaigns from ones that go straight to spam.

Infrastructure & Email Deliverability

Deliverability refers to whether your emails reach the primary inbox or end up filtered to spam. Your infrastructure setup plays a major role here. Poor configuration, no warm-up, or shared IPs with bad reputation can all tank your deliverability and harm your domain. The better your infrastructure setup, the better your inbox placement and reply rates.

Primeforge

Ideal if your prospects use Google Workspace or MS365 - using ESP Matching (sending from the same mailbox provider as your recipient uses) you can boost deliverability and make sure you land in their primary inbox.

Mailforge

Email infrastructure with a shared IP setup, perfect for when you’re just starting out or anticipating a large number of spam complaints.

Infraforge

Our most advanced, private email infrastructure made for heavy-hitters. With multi-IP provisioning and API, Infraforge is perfect for those needing customization and control at scale.

Frequently asked questions

If we don’t answer your question below, please contact us via chat

What is email infrastructure, and why does it matter in cold outreach?

Email infrastructure refers to the technical setup behind your cold email campaigns - domains, mailboxes, DNS records, sending IPs, and more. It directly affects whether your emails land in your recipient’s inbox or get flagged as spam. Without a proper infrastructure setup, your cold outreach won’t scale, and deliverability will suffer.

What’s the difference between shared, private, and ESP-native infrastructure?

Shared infrastructure means you’re using email resources (like IP addresses) alongside other senders. It’s easier to set up but comes with less control. Private infrastructure gives you full ownership and customization - ideal for high-volume or advanced users. ESP-native infrastructure uses trusted platforms like Google Workspace or Microsoft 365 to send emails, improving deliverability when targeting recipients on the same platforms.

How many domains and mailboxes do I need to start?

That depends on your sending volume. A healthy mailbox should only send around 30 to 50 cold emails per day. For example, to send 1,000 emails per day, you’d need around 20 to 30 mailboxes spread across 5 to 10 domains. You should also keep extra domains and mailboxes warming up in the background to replace any that get burned.

Do I need to warm up every mailbox and domain?

Yes. Sending from a cold domain or mailbox without warm-up will almost certainly trigger spam filters. Warmforge, included with every Salesforge subscription, handles warm-up automatically so you can build reputation before launching outreach campaigns.

What is ESP Matching, and how does it help deliverability?

ESP Matching means sending emails from the same provider your recipient uses - like Gmail to Gmail or Outlook to Outlook. Providers tend to trust emails sent within their own ecosystem more, which increases your chance of hitting the primary inbox. Primeforge is designed to help you take advantage of ESP Matching by offering both Google and Microsoft mailboxes.

What happens if one of my domains gets burned or blacklisted?

Domain burn is an unfortunate reality of cold outreach. That’s why we recommend maintaining a diverse infrastructure stack and always having unused domains and mailboxes warming up. If one domain is compromised, you can rotate in a new one without interrupting your sending schedule.

What DNS records do I need, and do I have to configure them myself?

You’ll need SPF, DKIM, and DMARC records to authenticate your emails and build trust with email providers. If you’re using Mailforge, Infraforge, or Primeforge, all DNS records are automatically configured for you during setup - no manual work needed.

How can I tell if my deliverability is good?

You should monitor metrics like health score, bounce rate, and inbox placement regularly. Warmforge gives you a health score for each mailbox (keep it above 97%), allows you to track bounce rates, and includes one free inbox placement test per month so you can see where your emails are landing.

Can I use multiple infrastructure types at once?

Absolutely - and in fact, you should. A diversified infrastructure stack helps spread risk, increase inbox coverage, and ensure you always have healthy domains ready to send. Many high-performing outbound teams combine Primeforge, Mailforge, and Infraforge to balance control, volume, and deliverability.

What’s the best option if I’m just getting started?

If you’re early in your outbound journey, Mailforge is typically the best starting point. It’s easy to set up, cost-effective, and shields you from some of the risks of private infrastructure. As you scale, you can add Primeforge or Infraforge for high-volume, custom setups.

Why can mailboxes only send 30 cold emails per day?

Cold emails are unsolicited messages, so mailbox providers apply much stricter filtering than they do for transactional or warm outreach. Sending more than 30 to 50 cold emails per day from a single mailbox increases the risk of spam flags, blacklisting, or even full account suspension - especially on platforms like Google Workspace or Microsoft 365. This limit isn't a hard technical cap; it's a best practice designed to keep your sender reputation healthy and ensure long-term inbox placement. Spreading volume across more mailboxes helps you scale safely.

Can the email warm up be less than two weeks?

Technically, yes - but it's risky. Some tools claim to offer "express" warm-up, but cutting the process short often leads to poor deliverability or immediate spam filtering. A two-week warm-up period is the minimum recommended time to simulate natural activity and build trust with mailbox providers. With Warmforge, the process is fully automated and designed to ramp up sending volume safely. If you rush it, you’re almost guaranteed to burn the mailbox before you even start your campaign.

What are placement tests and why are they important?

Inbox placement tests show you where your emails are landing across different providers - Gmail, Outlook, Yahoo, and others. Instead of relying on open rates (which are increasingly unreliable), these tests reveal whether your emails go to the primary inbox, promotions tab, spam folder, or somewhere else. This insight is crucial because if your message never hits the inbox, it doesn’t matter how good your copy is - no one will see it. With Salesforge, you get one free placement test per month via Warmforge to help monitor performance and catch deliverability issues early.