GreenArrow vs SuperSend: Cold Email Infrastructure Comparison

Teams evaluating their email infrastructure for 2025 often face a fundamental choice: build or buy. This is the core of the GreenArrow vs. SuperSend Relay comparison. Do you invest engineering resources into a self-hosted Mail Transfer Agent (MTA) like GreenArrow for total control, or do you leverage a managed infrastructure layer like SuperSend Relay to offload that complexity?

This is not a feature-for-feature comparison. GreenArrow is a powerful, low-level tool for building your own sending infrastructure. SuperSend Relay is the managed infrastructure you'd build on top of it, delivered as a service.

We'll compare the two from an operator's perspective, focusing on what matters at scale: engineering overhead, deliverability management, scaling capacity, and operational failure modes.

GreenArrow: The Self-Hosted MTA

GreenArrow is a Mail Transfer Agent (MTA) that you install and manage on your own servers. It gives you complete control over your sending infrastructure, from IP address configuration to mail routing rules. It's designed for organizations with a dedicated engineering or IT team that has the expertise to build and maintain a high-volume email system from the ground up.

1. What it is: Self-hosted mail transfer agent (MTA).
2. User profile: High-volume senders with an engineering team who require absolute infrastructure control.
3. Infrastructure approach: DIY. You provision, configure, and maintain the servers and software.

SuperSend Relay: Managed Email Infrastructure

SuperSend Relay is a managed infrastructure layer built specifically for high-volume cold outreach. It handles all the complex parts of deliverability—domain rotation, inbox warming, IP reputation, and scaling—automatically. It's designed for teams sending 10k to 1M+ emails per month who want enterprise-grade deliverability without hiring a dedicated engineer to manage it.

1. What it is: Managed enterprise email platform (ESP layer).
2. User profile: Growth teams, agencies, and SaaS companies who need to scale outbound without managing servers.
3. Infrastructure approach: Managed. We handle the servers, IPs, and deliverability automation for you.

GreenArrow

Throughput with GreenArrow is entirely dependent on the hardware you run it on and how well you configure it. Scaling from 100k to 1M emails/month involves significant engineering effort: provisioning more powerful servers, setting up load balancers, and carefully managing a larger pool of IP addresses. The ceiling is your team's ability to manage increasingly complex infrastructure without errors.

SuperSend Relay

SuperSend Relay is built on a cloud-native architecture designed for elastic scaling. The system is engineered to handle volume spikes and sustained high-throughput sending (10M+ emails/month) without user intervention. As your volume grows, the platform automatically allocates resources and optimizes domain/inbox rotation to maintain high deliverability. The scaling is automated, not manual.

Understanding how each system fails is critical for infrastructure decisions.

GreenArrow Failure Modes:

1. Configuration Risk: A small misconfiguration in your server settings or DNS records (SPF, DKIM) can halt sending or destroy your domain reputation instantly. Recovery is manual.
2. Server Downtime: If your server goes down, sending stops. You are responsible for monitoring, redundancy, and recovery, which often requires an on-call engineer.
3. Manual Scaling Failure: Attempting to scale too quickly without proper load balancing or IP allocation can lead to throttling and blocklisting.
4. IP Blacklisting: If one of your core IPs gets blacklisted, you are responsible for the entire delisting and recovery process.

SuperSend Relay Failure Modes:

1. Loss of Granular Control: Because it's a managed service, you can't tweak low-level MTA settings. You trade granular control for operational simplicity.
2. Platform Dependency: Your sending operation relies on the uptime and reliability of SuperSend's infrastructure. You are outsourcing the risk and management to a third party.
3. Compliance Constraints: For organizations with extremely strict data residency or on-premise requirements, a managed cloud service may not be compliant.

GreenArrow is the right choice when your organization has the resources and a strategic reason to own the entire infrastructure stack.

1. You have a dedicated engineering team with deep expertise in email protocols, MTAs, and deliverability.
2. Your business has strict compliance or security requirements that mandate self-hosted, on-premise infrastructure.
3. You need to build highly custom mail routing logic that isn't possible with a managed service.
4. You are already operating a large, mature self-hosted email infrastructure and have the processes to maintain it.

SuperSend Relay is the better choice for teams that want to focus on sending campaigns, not managing servers.

1. You are sending 10k-1M+ emails per month and want to scale without hiring a deliverability engineer.
2. Your primary goal is maximizing inbox placement, and you want to leverage automated warmup, domain rotation, and health monitoring.
3. You want to eliminate the operational overhead of server maintenance, software updates, and IP reputation management.
4. Your growth or sales team needs to move fast, and waiting on engineering resources to scale infrastructure is a bottleneck.

To be blunt, SuperSend Relay is not for everyone. We build trust by being honest about who we are not a good fit for.

You should stick with a self-hosted MTA like GreenArrow if:

1. You have a dedicated engineering team: If you already employ engineers specifically to manage email infrastructure, you may prefer the total control of a self-hosted solution.
2. You have strict on-premise requirements: If your compliance or security policies forbid using third-party cloud infrastructure for sending emails, a managed service is not an option.
3. You send very low volume: If you send less than 1,000 emails a month, the advanced infrastructure management of SuperSend is overkill.
4. You require deep, custom MTA-level configuration: If your use case demands unique routing rules or protocol-level modifications, you need the control GreenArrow provides.

The choice between GreenArrow and SuperSend Relay is a classic build vs. buy decision.

Choose GreenArrow if you have the engineering resources and a strategic need to build, control, and maintain your own email sending infrastructure from the metal up.

Choose SuperSend Relay if your goal is to achieve enterprise-grade scale and deliverability without the associated engineering headcount and operational complexity. It's the managed infrastructure layer that lets you focus on your outbound strategy, not your servers.