SDR Team Scaling Strategy: From 1 to 20+ Reps

Most companies scale their SDR team by adding more seats to their all-in-one sales tool and telling reps to send more emails. That was a viable strategy in 2018.

In 2025, that approach is a direct path to burning your primary domain, landing your entire team in spam, and capping growth. The fundamental mistake is treating outbound as a headcount problem. It's not. Scaling outbound is an infrastructure problem.

You can't just hire more reps and expect linear growth. Google, Microsoft, and other providers have gotten smarter. Your sending reputation is a shared, fragile asset. This guide outlines the infrastructure-first approach to scaling your SDR team, ensuring that your 20th rep is as effective as your first.

The traditional SDR scaling model is simple and deeply flawed. A company hires its first few SDRs, gives them a Salesforce seat and a plugin, and tells them to send from their corporate sdr@company.com inbox.

It works for a month. Then the problems start:

1. Single Point of Failure: Your entire outbound operation runs on your primary corporate domain. One SDR with a bad list or aggressive copy gets flagged, and the entire company's email deliverability suffers, impacting marketing, operations, and even executive communication.
2. Hard Sending Limits: Google and Microsoft enforce strict daily sending limits. Reps are forced to stop working, or they try to find workarounds that further damage reputation.
3. No Reputation Isolation: Good performers are dragged down by poor performers. There's no way to isolate risk. The entire domain's reputation is averaged out, usually towards the bottom.
4. Manual Management Nightmare: As you add reps, you're manually managing dozens of disconnected inboxes with no central view of deliverability health, warmup status, or domain reputation. It's unscalable and opaque.

An infrastructure-first approach treats your sending capability as a core asset to be built and protected, separate from your CRM and your reps. Instead of giving each rep an island, you build a shared, managed pool of resources they can all draw from safely.

This model is built on several key components:

1. Domain & Inbox Pools: You stop sending from your primary domain. Instead, you build a pool of dedicated sending domains (e.g., getcompany.com, trycompany.co) and dozens of inboxes (kurtis@getcompany.com, sarah@trycompany.co).
2. Automated Warmup: Every new inbox is automatically warmed up for weeks before it ever sends a cold email. This process builds a positive sending history with email providers.
3. Automated Rotation: Volume is spread across the entire pool of inboxes and domains automatically. No single inbox or domain sends too much, protecting the reputation of the entire system.
4. Centralized Deliverability Monitoring: You have a single dashboard to monitor the health of every domain and inbox, tracking placement tests (Inbox vs. Spam) and reputation scores.
5. Multi-Channel Integration: The infrastructure isn't just for email. It's the execution engine that coordinates email sends with LinkedIn connection requests and InMails, all from one centralized sequence.

Scaling isn't one-size-fits-all. Your infrastructure should match your team's size and volume. Here are three common setups.

The Starter Stack (1-3 SDRs):

1-2 dedicated domains, 3-5 inboxes, 75-125 cold emails/day (each inbox sends 25 cold + 25 warmup = 50 total/day) after a 2-3 week warmup. This is for teams just starting to build a dedicated outbound function. The goal is safety and proving the model.

The Growth Stack (4-10 SDRs):

2-3 dedicated domains, 10-15 inboxes, 250-375 cold emails/day (each inbox sends 25 cold + 25 warmup = 50 total/day) after a 3-4 week warmup. This is for teams with validated sequences who need to scale volume reliably across multiple reps.

The Enterprise Stack (10-20+ SDRs):

5+ dedicated domains, 25-50+ inboxes, 625-1,250+ cold emails/day (each inbox sends 25 cold + 25 warmup = 50 total/day) after a 4-6 week warmup. Built for high-volume operations, agencies, or large sales teams where protecting reputation at scale is paramount.

Transitioning to an infrastructure-first model doesn't happen overnight. It's a strategic shift that should be rolled out methodically.

Phase 1: Build the Foundation (Weeks 1-4)

Before you hire your next SDR, purchase your sending domains and set up your inbox pool. Start the warmup process immediately. This is the most critical step. Your infrastructure must be mature before you layer volume on top of it.

Phase 2: Standardize the Playbook (Weeks 5-6)

Centralize your best-performing sequences and messaging. Define the multi-channel steps (e.g., Email 1 -> LinkedIn View -> Email 2 -> LinkedIn Connection Request). Onboard your initial 1-3 SDRs onto this new, centralized system. They do not manage their own inboxes; they execute the playbook using the shared infrastructure.

Phase 3: Scale & Monitor (Ongoing)

With the foundation and playbook in place, you can now add new SDRs to the system. The onboarding is simpler: you grant them access to the platform, and they start using the pre-warmed infrastructure. Your primary focus shifts to monitoring deliverability metrics and optimizing sequence performance, not fixing broken inboxes.

You don't want your CRM managing this critical infrastructure. CRMs are databases of record, not high-volume sending engines. Their sending features are designed for transactional emails, not for managing the reputation of 50+ inboxes.

Likewise, simple mail-merge plugins don't provide the necessary infrastructure management for rotation, warmup, and deliverability monitoring. They put the entire risk of management on you.

SuperSend is built as the dedicated outbound execution and infra layer that sits alongside your CRM and data tools. It manages the complexity of domains, inboxes, warmup, and multi-channel sequencing so your team can focus on writing good emails and talking to prospects.

Once you have the infrastructure mindset, the next step is to explore proven multi-channel sequence patterns that can run on top of it.