These two products get compared constantly, and the comparison is usually framed wrong. Primeforge and Mailboundry are not competing implementations of the same thing. They are two different answers to the question of where your cold email physically comes from, and the right answer changes as your volume changes.
Primeforge sells real Google Workspace and Microsoft 365 mailboxes, priced per seat. Mailboundry is a dedicated sending platform where every mailbox gets its own IP, priced by volume tier. This piece is about which one your situation calls for, and what each really costs once you count everything you have to buy alongside it.
The fundamental difference
| Primeforge (Google / M365) | Mailboundry (private infra) | |
|---|---|---|
| What you get | Real Workspace or M365 seats | Dedicated IP per mailbox on our own ESP |
| Price | $4.50/mailbox/mo monthly, $4.00 annual | From $2.00/mailbox/mo |
| Billing terms | Monthly or annual | Monthly, quarterly or annual |
| Dedicated IP | Shared Google / Microsoft infrastructure | One per mailbox, included |
| Inherent sender trust | Highest available | Earned through warmup and behaviour |
| Cost curve | Linear, doubles when mailboxes double | Flattens as volume grows |
| Reply threading | Native Gmail / Outlook behaviour | Handled in the unified inbox |
| Best at | Named accounts, enterprise recipients | High-volume top-of-funnel |
| Sold as | Its own subscription | Part of the Outboundry subscription |
Where Google and Microsoft mailboxes win
Trust you cannot manufacture. A message from a genuine Google Workspace account starts with credibility that no private stack can replicate on day one. For enterprise recipients on Microsoft 365, mail arriving from another M365 tenant behaves differently in filtering than mail from an unfamiliar SMTP host. If you are emailing 200 named accounts at large companies, this is worth paying for.
Reply handling. Threads work the way recipients expect. Calendar invites, forwarding within the recipient’s company, out-of-office behaviour, all native.
Lower setup risk. Less depends on you warming correctly, because the platform reputation carries part of the load.
Outboundry sells the same thing Primeforge does, real Google Workspace and Microsoft 365 mailboxes with DNS automated, at $4 per mailbox per month on monthly billing. Primeforge charges $4.50 monthly and reaches $4.00 only annually. So if this is the model you need, the comparison collapses to the rate and to what else is in the box.
Competitor pricing taken from their public pricing pages at the time of writing. Prices change, verify current rates before you decide.
Where private infrastructure wins
Cost, decisively, past a point. Per-seat pricing is linear. Infrastructure pricing is not, because the marginal cost of another mailbox on an IP and domain you already control is close to zero. Somewhere between 50 and 100 mailboxes the two curves cross, and past the crossover the gap widens fast.
Reputation isolation. Every Mailboundry mailbox has its own dedicated IP. A campaign that generates complaints damages exactly one IP, not a pool. On shared infrastructure, and to a lesser extent within a single Workspace tenant, problems spread.
Domain and DNS control at scale. SPF, DKIM and DMARC generated automatically per domain, updatable in bulk across hundreds of domains at once, with domains purchasable in-app up to $14 per TLD. At forty-plus domains this stops being a convenience and starts being the thing that prevents silent failures.
No per-seat ceiling. Scaling from 50 to 500 mailboxes does not multiply the bill by ten.
The maths, at three volumes
Take three realistic setups and price the mailbox layer alone.
Small: 15 mailboxes, ~450 sends/day
Per-seat wins on every axis. At $4 each that is $60 a month ($67.50 at Primeforge’s monthly rate), and you get maximum sender trust for it. Private infrastructure at this volume is over-engineered, you would be paying for IP isolation you are not stressing.
Verdict: Google or Microsoft mailboxes.
Mid: 60 mailboxes, ~2,000 sends/day
This is the crossover zone and it is genuinely a judgement call. $240 a month in Workspace seats ($270 at Primeforge’s monthly rate) against roughly $120 for the same count of Mailboundry mailboxes at $2. The premium is defensible if your recipients are enterprise and reply quality matters more than raw volume. If you are running broad top-of-funnel, private infrastructure at a volume tier will cost less and give you per-mailbox IP isolation on top.
Verdict: split. High-value accounts on Workspace mailboxes, volume on Mailboundry.
Large: 200 mailboxes, ~7,000 sends/day
Per-seat pricing is now $800 a month for the mailbox layer alone, $900 at Primeforge’s monthly rate, before the sequencer, the warmup tool and the data subscription. The same 200 mailboxes on Mailboundry start around $400, with a dedicated IP each. Private infrastructure is not close on cost, and at this volume you need per-mailbox reputation isolation anyway, because with 200 mailboxes in play something will go wrong on one of them.
Verdict: Mailboundry, with a smaller pool of Workspace mailboxes reserved for named enterprise accounts.
The part the pricing pages leave out
Both Primeforge and Infraforge are single layers of a stack. Neither sends a campaign on its own. To run outbound you also need a sequencer, a warmup tool, a lead data source and somewhere to handle replies, in the Salesforge model, that is Salesforge, Warmforge and Leadsforge, each billed separately.
With Outboundry, the mailboxes and the Mailboundry infrastructure both sit inside a subscription that already includes cold email sequencing, LinkedIn outreach, 500M+ lead records, unlimited warmup, the unified inbox, AI personalization, the Reply Agent and ICP scoring. When you compare, compare the totals.
How to decide in one minute
- Under 30 mailboxes: Google or Microsoft mailboxes. Trust beats cost at this size.
- 30–80 mailboxes: split by campaign type. Enterprise and named accounts on Workspace, volume on private infrastructure.
- Over 80 mailboxes: private infrastructure as the base, with a Workspace pool for your highest-value targets.
- Volume that moves month to month: whichever provider bills monthly without penalty. Note that Infraforge, the private-infrastructure product on the Salesforge side, has no monthly plan at all, quarterly or annual only, plus $100 per additional dedicated IP.
Next: five Primeforge alternatives compared, or private infrastructure alternatives.
Frequently asked questions
Is Primeforge or Mailboundry better?
They solve different problems. Primeforge sells per-seat Google and Microsoft mailboxes, which carry the most sender trust. Mailboundry sells private infrastructure with a dedicated IP per mailbox, which is far cheaper per send at volume. Under roughly 50 mailboxes, real Workspace mailboxes usually win. Above that, private infrastructure does.
At what volume does private infrastructure become cheaper?
Roughly 50 to 100 mailboxes, or about 20,000 sends a month. Below that the per-seat premium for Google or Microsoft mailboxes buys you real deliverability advantage. Above it you are paying seat prices for what is fundamentally an IP and a domain.
Can I run both Google mailboxes and private infrastructure at once?
Yes, and most teams at scale should. Use Google or Microsoft mailboxes for named target accounts and enterprise recipients where trust and reply threading matter most, and private infrastructure for high-volume top-of-funnel. Outboundry runs both in one account.
Does Mailboundry give each mailbox its own IP?
Yes. Every mailbox gets a dedicated IP, so one campaign cannot damage the reputation of the others. That is the main structural difference from shared or pooled infrastructure.
Is Mailboundry billed annually?
No. Mailboundry bills monthly, quarterly or annually across five volume tiers, and you can move between tiers. That flexibility is the main commercial difference from most infrastructure providers in this category.