Comparing cold email infrastructure on price per mailbox is how people end up with the wrong setup. The per-mailbox number is real, but four different buying models sit behind it, per mailbox, per domain, per server, per seat, and which is cheapest depends entirely on your mailbox count.
So this is priced by model first, then by provider.
A note on prices. Checked in September 2026. Vendors re-tier often, so treat these figures as the shape of each offer rather than a live price list and confirm before you buy.
The four buying models
| Model | Cost shape | Cheapest when |
|---|---|---|
| Per mailbox | Linear, usually with volume tiers | Almost always, under about 100 mailboxes |
| Per domain | Step function, you pay to fill the domain | You genuinely fill each domain, which concentrates risk |
| Per server | Fixed capacity, unlimited mailboxes | Large estates, past the crossover |
| Per seat (Google / Microsoft) | Linear and never flattens | Small setups, or when inherent sender trust matters most |
The providers
| Provider | Model | Price | Dedicated IP | Platform included |
|---|---|---|---|---|
| Mailboundry | Per mailbox, volume tiers | $2.50 falling to $2.10 monthly; $1.70–$1.30 annual; managed pools from $0.80 | Optional, from $1.30; extra IPs $50/mo | Yes |
| Mailforge | Per mailbox, 10-slot minimum | From about $3 monthly, ~$2 annual | Not offered | No |
| Mailpool | Per mailbox, pay as you go | $2.50 / month | Not in the standard offer | No |
| Mailreef | Per server, screened customers | Not published, quoted after a demo | Yes, per server | No |
| ScaledMail | Managed packages | Google ~$3.50/inbox; Azure ~$50/domain for 25; SMTP ~$3.75/domain for 4 | Shared provider IPs with rotation | No |
| Google / Microsoft | Per seat | ~$4 / mailbox / month, plus ~$14 / domain / year | Shared provider infrastructure | No |
| Azure | Per domain | ~$25 / domain for 50 mailboxes | Shared Microsoft infrastructure | No |
The crossovers that actually decide it
Google/Microsoft versus everything else: about 7 mailboxes. Per-seat pricing at roughly $4 a mailbox never flattens, so above a handful of mailboxes it is the most expensive route by a wide margin. Below that, the inherent sender trust of a provider-backed mailbox is worth the premium and the setup is trivial. The full per-mailbox arithmetic.
Azure versus per-mailbox: it depends on filling the domain. About $25 per domain for 50 mailboxes is roughly $0.50 a mailbox, the cheapest number on this page, if you use all 50. Nobody should put 50 mailboxes on one domain, because reputation is domain-level and a burn takes all 50 with it. Price it honestly at the mailbox count you would actually run per domain, and it stops being remarkable.
Per server versus per mailbox: roughly 40 mailboxes. Under that, fixed capacity is the worst deal in the category. Well over it, it can be the best.
Shared pool versus dedicated IP: about 1,500 sends per IP per month. This is the one that is not about money. Below the threshold a dedicated IP underperforms a well-managed pool, because thin traffic gives filters too little signal. Above it, pooled reputation becomes your ceiling. The full argument.
The question that matters more than price
If you buy pooled infrastructure, the only thing that determines your placement is whether the pool is managed or unmanaged. A pool with entry vetting, enforced ramps, complaint monitoring and rotation behaves like infrastructure. An open-enrolment pool where anyone can buy ten slots and upload a purchased list is a lottery.
You cannot audit this from outside, so ask directly, and ask what happens to a customer whose complaint rate climbs after signup. Screening at the door with no enforcement afterwards is half a control.
What to add to the price before comparing
- Domains at roughly $6 to $14 a year each, and you need one per two or three mailboxes.
- Warmup. Included by some, a separate product for others. At 40 mailboxes this is not a rounding error.
- The sending platform. Most infrastructure vendors do not include sequencing, lead data or an inbox. The mailbox line is usually the smallest part of the real bill.
- Reporting. Occasionally a per-inbox add-on, which at 100 inboxes is a meaningful monthly line.
- Setup time. Minutes and self-serve, 24 to 72 hours managed, or after a call. If you need to send this week, that is a hard filter.
Recommendations by situation
| If you are | Start with |
|---|---|
| Under 10 mailboxes, testing the channel | Google or Microsoft seats. Highest trust, trivial setup, and the premium is small at this size |
| 10–100 mailboxes | Per-mailbox with tiers and both IP models available, so growth is not a vendor change |
| Volume that moves month to month | Pay-as-you-go per mailbox. An annual commitment prices your quietest month as your baseline |
| An agency with many clients | Per-client domain and IP isolation, whatever the model. One client’s bad list must not reach another’s placement |
| Past 200 mailboxes | Price the server model against per-mailbox tiers, and be ready to book a call |
| Unwilling to learn DNS | A managed reseller. The setup work removed is genuinely worth the premium |
Next: the same question costed at 10, 100 and 500 mailboxes, the shared versus dedicated threshold, or how many mailboxes you actually need.
Frequently asked questions
What is the cheapest cold email infrastructure?
Per-mailbox pricing with volume tiers is cheapest for most teams under about 100 mailboxes, with vetted managed pools from around $0.80. Azure looks cheaper per mailbox but is priced per domain for 50 mailboxes, which nobody should actually run on one domain.
When does Google or Microsoft stop making sense?
At around seven mailboxes. Per-seat pricing at roughly $4 a mailbox never flattens, so above a handful it becomes the most expensive route. Below it, the inherent sender trust is worth the premium.
When is server-based pricing worth it?
Past roughly 40 mailboxes. You pay for fixed capacity whether you use it or not, so it is the worst deal at small scale and potentially the best at large scale.
Do I need a dedicated IP?
Only above about 1,500 sends per IP per month. Below that a well-managed shared pool outperforms a dedicated IP, because thin traffic gives filters too little signal to form a view.
What should I ask a pooled provider?
Whether the pool is vetted at signup, whether ramps are enforced, whether complaint rates are monitored afterwards, and what happens to a customer whose complaints climb. Screening with no ongoing enforcement is half a control.