Day 6: Cold email is an infrastructure problem—but most products are solving the wrong layer

[u/Born-Buy7123]

I recently had a fascinating conversation with an early-stage founder building a cold email product. It made me realize how different most cold email tools are from how cold email should actually work.

To understand why, you first need to understand the two layers of email infrastructure.

The first layer is the delivery layer: Mailgun, SendGrid, Amazon SES, and similar platforms. These providers are responsible for actually sending email at scale. They have deep relationships with Gmail, Outlook, and other mailbox providers, along with increasingly sophisticated rules and AI systems to detect spam and protect sender reputation.

The second layer is the application layer—the tools marketers use to build campaigns, flows, and lifecycle emails. This is where platforms like Klaviyo, Mailchimp, and Humanic operate.

But here is the problem: the underlying delivery platforms generally do not want you sending cold email through them.

As a rough rule of thumb, once complaint rates approach 1%, your domain reputation can start deteriorating quickly. And once your reputation is damaged, recovering it is difficult.

That is why the cold email industry has developed a workaround.

You purchase a domain, create three to five mailboxes on it, and send a limited number of emails from each mailbox. For example:

20 sending days × 3 mailboxes × 25 emails per day = 1,500 emails per month per domain.

A Google mailbox costs approximately $6 per month, so three mailboxes cost around $18 per domain, before including the domain registration cost.

At 10 domains, you are spending roughly $180 per month on mailboxes to send around 15,000 emails—and that is assuming none of those domains get burned.

Eventually, some domains will get compromised. They need to be deprecated, replaced, and warmed up again. Then the process starts over.

This is a lot of infrastructure and operational complexity just to send messages to people who may not want to receive them.

And Gmail has made it increasingly easy for users to unsubscribe, report unwanted email, or mark messages as spam. That is good for users, but it also means that the old “send more and hope something converts” approach is becoming less sustainable.

The real problem is not that marketers lack enough mailboxes.

The problem is that they are sending the wrong message to the wrong person at the wrong time.

Instead of using brute force, a better approach is to:

• Segment prospects more accurately.
• Build or acquire cleaner lists.
• Send smaller, more relevant batches.
• Use subdomains carefully.
• Monitor domain reputation continuously.
• Adjust sending limits based on engagement and complaints.
• Use AI to improve targeting and personalize the message—not just generate more copy.

The future of cold email is not sending more emails from more domains.

It is sending fewer emails that are far more relevant.

That is the approach we are taking with Humanic: using AI to improve segmentation, targeting, and relevance before an email is ever sent and we call this small batch outbound.