The Cold Email Task

When I was tasked with building a cold email marketing machine for a client, I knew that simply relying on third-party solutions wouldn’t give me the level of control and scalability I needed. I wanted a solution that could handle high volumes of emails while minimising the risk of blacklisting and maintaining good domain reputations. So, I decided to build my own infrastructure from scratch, and the results have been nothing short of impressive.

The Foundation: ISPConfig Multi-Server Setup

The first step in my process was setting up an email server infrastructure using ISPConfig, a powerful multi-server solution for Debian and Ubuntu. I followed the tutorial from HowtoForge to get the servers configured and working together as a cohesive system.

To ensure scalability, I created a cluster of 25 servers, each responsible for a single domain name. These servers are all connected to a frontend server that handles incoming email traffic. Depending on the domain, the email is routed to the specific server responsible for that domain, then sent out. This setup is incredibly efficient because it centralises the configuration while allowing me to manage each domain’s email reputation separately.

Domain Strategy: Maturing Domains for Reputation

I also purchased a number of domains for my client, allowing them to mature for 23 months. This maturation process is key to building up a good domain reputation, which is essential when sending high volumes of cold emails. By spreading the email load across multiple domains, I can ensure that no single domain gets overwhelmed and flagged by spam filters.

Benefits of the Multi-Server Setup

With this infrastructure, the email marketing system benefits from several key advantages:

1. Spread Across 25 Domains: Each of the 25 domains handles only a portion of the total email load, making it less likely that any one domain will be flagged as a spammer. By distributing the emails evenly, I can scale the client’s outreach without compromising their sender reputation.
2. Minimising Blacklisting Risk:
   Because each domain only sends a small percentage of the total emails, the risk of being blacklisted is dramatically reduced. If one domain faces an issue, it’s easy to switch to another domain in the cluster, maintaining continuity in the campaign.
3. Failover System:
   If one server encounters an issue, the system automatically routes emails through other servers, ensuring that the campaign doesn’t grind to a halt. This failover system keeps the email flow steady and prevents interruptions.
4. Maintained Domain Reputation:
   Since each domain sends a smaller volume of emails, each one’s reputation remains strong. Email providers are more likely to accept emails from a domain with a low volume of outbound messages, reducing the chances of being flagged as a spammer.

Results: Growing and Improving Month Over Month

Now that the system has been running for over a year, the results are continuing to improve month after month. The client is seeing a steady increase in open rates, response rates, and conversions, with far fewer issues related to deliverability.

By building my own email server infrastructure and integrating it with Instantly.ai, I’ve created a robust, scalable system that continues to deliver top-tier results.

Conclusion: Why Custom Infrastructure Works

Building my own custom email server infrastructure on ISPConfig allowed me to have complete control over the process, ensuring scalability, security, and high deliverability for my client. While third-party services can be useful, there’s no substitute for a setup designed specifically for the needs of the campaign.

The results speak for themselves, and I’ll continue to refine and expand the system as the client’s needs grow. Custom infrastructure might require more upfront effort, but the payoff in terms of control, flexibility, and long-term success is well worth it.