Operator guide

Agency Cold Email Infrastructure Stack

Agencies need repeatable, client-separated infrastructure that is easy to support when campaigns are live.

Separate every clientStandardize DNS and launch checksReview deliverability weekly

Calculate my setup → Get an infra plan

24–72h

target launch window once requirements are clear

100

Outlook inboxes included per domain package

2 lanes

Google Workspace for quality, Microsoft 365 for scale

Field Guide

Quick Answer

An agency cold email stack needs client-separated domains, Google and Microsoft inbox planning, SPF, DKIM, DMARC, tracking domains, warmup rules, sequencer connections, replacement processes, and weekly deliverability review.

Core Components

The stack should include domain pools by client or campaign, an inbox plan based on daily send targets, provider mix, DNS templates, sequencer integration, bounce monitoring, and pause rules.

Agency-Specific Risk

One client’s bad list should not damage another client’s infrastructure. One blocked domain should not stop the whole agency. One junior operator should not accidentally push a new domain too hard.

Operating Rhythm

Before launch, check DNS and inboxes. Daily, monitor bounces and replies. Weekly, review domain and inbox health. Monthly, review provider mix and cost.

Pricing model

Plan infrastructure by usable sending capacity.

Cheap inboxes get expensive when DNS is wrong, replacements are unclear, or campaigns sit blocked. Price the system, not just the mailbox.

Microsoft 365 / Outlook

$70/mo per domain100 inboxes included

Best for low-cost scale
Useful for provider diversification
Requires conservative send limits

Google Workspace

$3.50/mo per inbox5 inbox minimum

Best for Gmail-heavy audiences
Higher-quality lane for valuable accounts
Use controlled ramp-up, not brute force

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Setup quality

SPF, DKIM, DMARC, MX, forwarding, and sequencer connection need to be right before volume starts.

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True cost

Warmup time, replacement policy, support, and DNS mistakes change the real cost per usable inbox.

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Best fit

Built for operators who want managed infrastructure and fast human help across multiple campaigns.

Decision framework

How to choose the right inbox setup

Use the provider mix as a portfolio decision. One lane gives simplicity. Two lanes give resilience.

Use Google Workspace when

Your prospects are Gmail-heavy.
Placement quality matters more than lowest unit cost.
You are running smaller, higher-value campaigns.

Use Microsoft 365 when

You need lower-cost scale.
You want provider diversification.
You can spread volume conservatively across many inboxes.

FAQ

Common questions

How many inboxes do I need?

Start conservative. Use the calculator to map daily send goals into inbox count, domain count, and provider mix.

Should I use Google Workspace or Microsoft 365?

Google is stronger for Gmail-heavy audiences. Microsoft 365 can lower cost and diversify infrastructure. Serious operators often use both.

What matters more than price?

DNS accuracy, send limits, replacement policy, support speed, and domain isolation matter more than saving a few cents per inbox.

Next step

Need this sized for a real campaign?

Send daily volume, number of campaigns or clients, provider preference, and sequencer. We’ll map inboxes, domains, and monthly cost.

Request quote →Use calculator