Supersend has one feature that sets it apart from most sequencers: BYOI — Bring Your Own Infrastructure. You can connect external domains and mailboxes via API key rather than relying on Supersend's in-app provisioning. That one capability makes Supersend one of the cleanest pairings with ScaledMail in the market.
The model is simple: Supersend handles sequencing, multichannel orchestration, reply management, and CRM integrations. ScaledMail provides the managed infrastructure you bring. Your infrastructure stays under expert management. Supersend's campaign engine runs through it.
Here's how to set it up and why separating infrastructure from sequencing produces better deliverability outcomes at scale.
Why BYOI Changes the Equation
Most sequencers treat infrastructure as a locked-in feature — you buy their inboxes, use their warmup, and accept whatever deliverability outcomes follow. Supersend's BYOI model acknowledges that serious senders want to own their infrastructure choices.
When you bring your own infrastructure to Supersend, you control:
- Which email service providers your inboxes run on (Google Workspace, Microsoft 365, SMTP)
- How warmup is managed and at what ratio
- Who monitors deliverability and responds to issues
- How domains are selected, aged, and rotated
- Whether your infrastructure is isolated from other senders
ScaledMail handles all of that. You connect ScaledMail Google Workspace and Microsoft 365 inboxes to Supersend via OAuth (one-click authorization) or API key. Supersend runs campaigns through them. The division of labor is clean and explicit.
Supersend's In-App Infrastructure vs. ScaledMail
Supersend offers in-app domain and mailbox purchasing with auto-DNS configuration. This is genuinely convenient — buy domains, get DNS configured automatically, start warming inboxes without touching a DNS panel.
ScaledMail takes it further with ongoing managed infrastructure. Auto-DNS configuration is a great start. ScaledMail adds continuous deliverability management on top — warmup maintenance, blacklist monitoring, domain rotation, reputation diagnostics, and remediation handled by a dedicated team.
Across 217,600+ managed inboxes, we've learned that cold email infrastructure has a maintenance burden that scales with your operation. At 10 inboxes, you can manage it yourself. At 50 inboxes across multiple clients, it becomes a part-time job. At 200+ inboxes, it's a full operational function. ScaledMail is that operational function — so you focus on campaigns, not infrastructure.
Shared vs. Isolated Infrastructure
ScaledMail gives you isolated M365 and Google Workspace tenants — your organizational environment is completely separate from any other customer's infrastructure. Your sender reputation within those ESPs is determined entirely by your own sending behavior. That isolation is the foundation for stable, predictable deliverability at scale.
Multi-ESP Diversification
ScaledMail runs Google Workspace, Microsoft 365, and SMTP across isolated tenants — and actively diversifies across ESP types for teams that need it. When Google tightens spam filtering, Microsoft inboxes continue delivering. Mixed-ESP coverage keeps campaigns resilient through any single provider's policy changes.
Pre-Aged Domains
Supersend's automated warmup is a legitimate feature. But warmup still takes time — fresh domains need 14+ days before safe cold sending. ScaledMail's pre-aged domains (30, 90, and 180 days old) skip that window. Order on Monday, campaigns live by Wednesday. For agencies where client onboarding speed matters, pre-aged domains are the answer.
The Full Stack: ScaledMail + Supersend
Here's how responsibilities split:
- ScaledMail: Domain purchasing, DNS authentication (SPF, DKIM, DMARC), mailbox provisioning on Google Workspace and Microsoft 365, compatible with all warmup tools maintaining the 2:1 ratio permanently, deliverability monitoring, domain rotation, blacklist remediation, dedicated Slack channel
- Supersend: Multi-channel sequences (email + LinkedIn), Super Inbox for unified reply management, reply categorization (Interested, Not Interested, OOO, etc.), A/B testing with spintax and personalization, CRM integrations (HubSpot, Pipedrive, Slack), campaign analytics
ScaledMail Google Workspace and Microsoft 365 inboxes connect to Supersend via BYOI — via OAuth (one-click authorization) or API key, depending on Supersend's connection method for external inboxes. Supersend runs campaigns through them. ScaledMail keeps those inboxes healthy.
Setup: Connecting ScaledMail to Supersend
Step 1: Plan Your Infrastructure
Book a call or run numbers through the infrastructure calculator. We need:
- Target daily cold email volume across all campaigns
- Number of active clients and campaigns
- ESP preference (Google, Microsoft, or a mix — we recommend both)
- Launch timeline and whether pre-aged domains are needed for a fast start
Volume planning: 15-25 cold emails per inbox per day on Google Workspace, 5-10 per day on Microsoft 365 through ScaledMail's managed accounts. Every inbox is compatible with the 2:1 warmup ratio maintained permanently via your warmup tool — for every cold email sent, 2 warmup emails maintain active sender reputation. This ratio runs indefinitely, not just during initial ramp-up.
Example: to send 1,000 cold emails per day across 5 campaigns, plan for roughly 50-65 Google inboxes across 25-32 domains, plus 20-25% rotation buffer. Supersend's Growth plan ($99/mo) supports 50K emails/month — that's roughly 1,650/day, enough headroom for this volume.
Step 2: Infrastructure Build
Our team handles the complete build while you focus on campaign strategy:
- Domains: Selected and purchased following cold email best practices — .com preferred, no hyphens, no numbers, no spam-associated keywords. Every domain forwards to your business website so prospects can verify you're real.
- DNS: SPF, DKIM, and DMARC configured and verified on every domain. We monitor DKIM propagation and confirm all records resolve correctly before declaring inboxes ready.
- Mailboxes: Google Workspace and/or Microsoft 365 accounts provisioned on isolated tenant infrastructure. Your M365/Google account environment is separate from other customers.
- Warmup: ScaledMail is compatible with all warmup tools — connect your warmup tool and activate the 2:1 ratio from day one. Fresh domains run 14-day warmup. Pre-aged domains validate existing reputation and move to campaign-ready faster.
Standard 40-inbox build: 24-48 hours. You don't touch DNS.
Step 3: Connect to Supersend via BYOI
Once inboxes are verified and healthy, we provide credentials. In Supersend:
- Go to Email Accounts → Add Mailbox → select Custom / BYOI
- For Google Workspace and Microsoft 365 inboxes, select Google or Microsoft and authorize via OAuth — select your account in Supersend's connection flow. If Supersend's BYOI flow requires SMTP credentials instead, we provide those as a fallback.
- Set the daily sending limit to exactly the number ScaledMail specifies per inbox
- For API-based connections (Supersend supports up to 2,000 senders via API), contact us — we'll provide credentials in the format Supersend's API expects
For bulk builds (30+ inboxes), we'll deliver credentials in a structured format compatible with Supersend's import flow.
Step 4: Configure Supersend Campaigns
With ScaledMail inboxes connected, configure campaigns to protect the infrastructure:
- Daily sending limits: Use exactly the numbers ScaledMail specifies per inbox. These are calculated to maintain the 2:1 warmup ratio and stay within ESP-specific safe zones. Supersend's volume-based pricing (50K/mo on Growth, 200K/mo on Scale) gives you headroom — don't fill it all from a small inbox pool.
- Sending window: 8am-6pm recipient timezone for B2B. Supersend's scheduling handles timezone targeting.
- Open tracking: Disable it. Apple Mail Privacy preloads email content, making open data meaningless. Tracking pixels also trigger spam filters. Track replies only — Supersend's Super Inbox handles this well.
- Sequence length: 1-2 email touches maximum, then 90 days dark. Most replies come from email #1. Additional email touches spike spam complaints and accelerate domain burn. Supersend's LinkedIn integration fills the follow-up gap without email risk.
- Bounce rate: Target under 1.5%. Verify all lists through LeadMagic and BounceBan before uploading to Supersend. If Supersend shows bounces climbing above 1.5%, pause and re-verify.
Using Supersend's Super Inbox with ScaledMail Infrastructure
Supersend's Super Inbox — which aggregates email and LinkedIn replies into a single view with reply categorization — works better when your email infrastructure is clean. Here's why: when inboxes have deliverability issues, a portion of your sent emails never reach recipients, and your reply inbox looks artificially quiet. It's easy to misread this as a targeting or copy problem.
With ScaledMail's managed inboxes running clean sender reputation, the replies coming into Supersend's Super Inbox are an accurate signal. Interested vs. Not Interested categorization becomes meaningful data rather than noise from unreliable delivery.
The same principle applies to Supersend's A/B testing with spintax and personalization. A/B test results are only interpretable when deliverability is consistent across variants. If Inbox A sends through healthy infrastructure and Inbox B sends through degraded infrastructure, you're not measuring copy — you're measuring deliverability variance. ScaledMail eliminates that variable.
Domain Rotation Strategy
We manage domain rotation using a 2-batch system:
- Batch A: Active sending for 3 weeks
- Batch B: Resting, with minimum daily sends to maintain warmup engagement
- After 3 weeks, batches swap
In Supersend, this means we periodically update which inboxes are in your active pool. We handle the scheduling and notify you in your dedicated Slack channel when batches rotate. You always have fresh, healthy inboxes available — Supersend's campaign engine always has healthy senders to work with.
Domain longevity: high-engagement campaigns run 12-18 months. Lower engagement: plan to rotate every 5 months. If you're burning through domains every 1-2 months, the issue is copy or list quality, not infrastructure. Supersend's A/B testing with spintax is the right diagnostic tool there.
Scaling to 2,000 Senders via Supersend's API
Supersend supports up to 2,000 email senders via API — a feature designed for agencies and teams running large sender pools. ScaledMail is the right infrastructure provider for this scale.
At 2,000 senders, you need:
- Proper ESP diversification across Google and Microsoft to avoid single-provider policy risk
- Isolated tenants to prevent cross-campaign reputation contamination
- Active warmup maintenance on every inbox via your warmup tool (not just initial warmup)
- Domain rotation management across hundreds of domains
- Continuous blacklist monitoring and remediation
- A team that knows what's happening across the entire pool
Managing this manually isn't viable. It's an operational function. ScaledMail is that function. We provision, maintain, and monitor the infrastructure. You focus on campaigns.
Diagnostics: When Something Goes Wrong
Supersend surfaces campaign-level signals — reply rates, bounce rates, categorized responses. ScaledMail monitors infrastructure-level signals — blacklists, DNS health, warmup engagement, ESP-level reputation. Together you have two diagnostic layers:
| Symptom | Likely Cause | Fix |
|---|---|---|
| Reply rate drops sharply | Copy fingerprinting — ESPs detected repeated content patterns across many sends | Rewrite body copy entirely. Use Supersend's spintax to increase variation at scale. |
| Reply rate declines over weeks | Domain/inbox reputation degradation | ScaledMail rotates to rested batch. Alert us in Slack and we'll accelerate the rotation. |
| Deliverability test shows spam | DNS issue or domain blacklisting | ScaledMail diagnoses and remediates. We monitor blacklists proactively and typically catch this before you do. |
| Healthy deliverability, low replies | Copy or targeting problem | Use Supersend's A/B testing with spintax. Test different angles, subject lines, and offers. Infrastructure is fine. |
| Bounce rate above 1.5% | List quality issue | Pause campaigns. Re-verify through LeadMagic + BounceBan before uploading again to Supersend. |
| Super Inbox shows unusually low reply volume | Could be deliverability issue or copy issue | Check Supersend's delivery data first. If sent volume looks normal but replies are absent, message ScaledMail Slack for infrastructure diagnosis. |
Frequently Asked Questions
Does ScaledMail work with Supersend's automated warmup?
Yes. ScaledMail is compatible with all warmup tools — warmup is not included in ScaledMail but works alongside it. If you're using Supersend's built-in automated warmup, keep it running to maintain the 2:1 ratio on ScaledMail inboxes. Additional positive engagement signals strengthen sender reputation. There's no conflict between the two systems — more warmup engagement is always better than less.
How does Supersend's BYOI API connect to ScaledMail inboxes?
Supersend's BYOI API connection accepts SMTP credentials or OAuth tokens for external inboxes, depending on the account type. For Google Workspace and Microsoft 365 inboxes, OAuth is the primary connection method. We provide credentials in a structured format that maps directly to Supersend's API schema. For large-scale API connections (hundreds of inboxes), we'll coordinate the credential delivery format with your technical team.
Which Supersend plan do I need for ScaledMail infrastructure?
Any Supersend plan supports BYOI. The Growth plan ($99/mo, 50K emails/month) is sufficient for most teams under 50 daily active inboxes. The Scale plan ($249/mo, 200K emails/month) fits higher-volume operations. ScaledMail's infrastructure cost is separate from your Supersend subscription.
Can I use ScaledMail for some campaigns and Supersend's in-app inboxes for others?
Yes. Both inbox types can coexist in the same Supersend workspace. Some agencies use ScaledMail for high-priority client campaigns (where deliverability is critical) and Supersend's in-app provisioning for lower-volume or test campaigns.
How fast can ScaledMail inboxes be live in Supersend?
Pre-aged domains: 24-48 hours from order to campaigns running. Fresh domains: 14-day warmup period, then live. For agencies that need speed, pre-aged domains are the right call.
What if I already have domains set up through Supersend and want to migrate to ScaledMail?
The cleanest migration approach: keep Supersend-provisioned inboxes running on active campaigns while ScaledMail inboxes warm up for new campaigns. Once ScaledMail inboxes are ready, migrate campaigns over incrementally. We can advise on the transition sequence to avoid any deliverability gap.
Get Started
Running Supersend with BYOI and ready for managed infrastructure that scales with your campaigns? Book a call to spec your setup, or use the infrastructure calculator to build your package.
Month-to-month. No annual lock-in. Pre-aged domains available for same-week launch.