Most cold email teams discover the economics of per-mailbox pricing the hard way: somewhere between the 15th and 30th mailbox, the monthly invoice stops making sense. The per-seat cost looked fine at mailbox #1. It is brutal at mailbox #30. This is the math nobody shows you until you are already locked in.
The three pricing models
Cold email infrastructure is sold under three pricing shapes. They produce very different outcomes once you pass a few mailboxes.
1. Per-mailbox (per-seat)
Google Workspace, Microsoft 365, most shared-infrastructure cold email platforms. You pay per mailbox per month, usually $6-$20 per seat depending on tier.
Shape: linear. 10 mailboxes cost 10x one mailbox. 50 mailboxes cost 50x. There is no volume break.
2. Per-mailbox with tiered volume discount
Some shared providers offer step discounts: 10% off at 25 mailboxes, 15% off at 50. Softens the slope but does not change the shape.
Shape: still linear, just with a shallower slope. The 100th mailbox still costs something close to the 1st.
3. Flat-rate per server
Dedicated VPS providers (SendChief falls here) sell by server size, not per mailbox. Within a plan tier, the marginal cost of an additional mailbox is zero.
Shape: step function. Cost jumps when you outgrow a tier, then is flat until the next one.
The math at real volume
Let's do 50 sending mailboxes, because that is where agencies and in-house outbound teams actually live. Pricing as of early 2026, rounded for clarity.
Google Workspace Business Standard
$14/user/month × 50 mailboxes = $700/month, $8,400/year. That does not include any cold-email-specific tooling, warm-up, or IP reputation monitoring.
Microsoft 365 Business Basic
$6/user/month × 50 mailboxes = $300/month, $3,600/year. Cheaper on paper, but 365 has stricter outbound throttling and stronger anti-outbound filtering, which makes it a worse base layer for cold email specifically.
Shared cold email platform (typical)
$5-$10 per mailbox for the cold-email-focused product, on top of the underlying workspace fees. At the $8 midpoint: 50 × $8 = $400/month on top of the workspace. Total with Workspace base: roughly $1,100/month.
Dedicated VPS (SendChief Medium tier)
$149/month flat, up to 50 mailboxes, 15 sending domains, dedicated VPS with production-grade mail server included.
Monthly cost per mailbox at 50 mailboxes: $2.98. No per-seat fees, no workspace layering, no volume negotiation.
The gap, year over year
Over 12 months at 50 mailboxes:
- Google Workspace only: $8,400
- Google Workspace + shared cold-email layer: ~$13,200
- Microsoft 365 only: $3,600
- SendChief Medium: $1,788
The difference between Google Workspace + shared cold-email infrastructure and a dedicated VPS is about $11,400 per year, or roughly the cost of one decent SDR.
Why per-mailbox pricing exists
Per-seat pricing exists because Google and Microsoft price their underlying Workspace seats that way — anyone reselling on top has to pass that shape through. The cost structure of a shared-infrastructure provider is driven by the underlying Workspace bills, not by what it actually costs to run a mail server.
A dedicated VPS decouples from that entirely. The underlying cost is the VPS itself (a few tens of dollars a month), plus the operational cost of the provisioning and monitoring stack. Adding a mailbox on an existing VPS costs effectively nothing, because a production-grade mail server handles hundreds of mailboxes on modest hardware.
The break-even point
Roughly:
- 1-10 mailboxes: per-seat pricing is competitive and sometimes cheaper.
- 10-20 mailboxes: flat-rate pulls ahead. The gap is small but clear.
- 20-50 mailboxes: the gap becomes painful. At 50 the dedicated VPS is ~2.5x cheaper than a per-seat stack.
- 50+ mailboxes: per-seat pricing is a tax you are paying because you have not migrated yet.
How to think about migration
The migration cost from a per-seat platform to a dedicated VPS is mostly one-time labor: re-provisioning domains, warming up new IPs, updating sending tool credentials. Two to three days for 50 mailboxes with the right tooling. Against $11k/year of ongoing savings, payback is under a week.
The real friction is usually emotional: operators who have been on Google Workspace for years get nervous about moving outbound off it. The nervousness is a signal worth paying attention to — but the math is unambiguous. At real volume, per-seat pricing for cold email is a cost you have been trained not to question.
Related resources
There is an interactive version of this math on the Escape Google Workspace page that lets you plug in your own mailbox count and see the year-over-year gap. See the cost calculator for the numbers against your own setup.