Wholesale email infrastructure for the people who sell email infrastructure

If you're starting an ESP today — or trying to graduate an existing reseller business into one — the architecture decision is the most expensive decision you'll make. Get it wrong and you spend the next eighteen months migrating off it under customer pressure. Get it right and the platform compounds: every new customer adds margin without adding an engineer.

The three real options:

Build it yourself. Buy a PowerMTA license at $8,000/year minimum (more for dev/test environments — that's an extra line item the original vendor charges separately), put it on bare metal you rent from Hetzner or OVH, hire someone who knows MTAs, build the abuse-detection and reputation-monitoring layer that your customers will eventually demand. Add KumoMTA in 2024-2025 as a real open-source alternative if you don't want the PowerMTA license, but understand that you're trading commercial license cost for engineering depth — Postmastery integrations, the analytics tooling, the support contract — none of which are free either.

Buy SES Tenants and resell that. Amazon SES Tenants launched in August 2025 with the explicit pitch of letting ISVs sell to thousands of downstream customers. The math at $24.95 per dedicated IP per month plus the per-message rate is reasonable, the AWS support contract gives you something to point at when an enterprise customer asks. The trade-off is that you've built your business on top of a US-jurisdiction operator, your dedicated IP costs are USD-denominated and IP-stocked, and you're competing on the same primitives your customer would get directly from AWS if they bothered to look. Some ESPs do this and it works. Most discover that "infrastructure rebought is infrastructure with no margin."

Resell our wholesale. We sell you the operator-managed PowerMTA stack — bare-metal Xeon servers, dedicated IP allocations from /24 ranges we own, FBL ingestion, daily DNSBL monitoring, a Stockholm on-call rotation when something needs human eyes — at flat EUR pricing without per-IP add-on lines. Your reseller account gets sub-account isolation per customer (the same per-tenant primitives we ship to SaaS platforms), so a bad customer can't crater the rest of your book. You set retail prices. We never see your customer list.

The structural question isn't really "which is cheapest." It's "which one has the lowest probability of forcing me to migrate everything in eighteen months?" The answer changes by whether your customer base is single-digit thousands of small senders or double-digit enterprise contracts, by whether you need EU operator residency for procurement reasons, and by how much engineering you actually want to do.

The reseller relationship is contractually simpler than most people expect. We sign a wholesale agreement with you that gives you a managed PowerMTA tier (your choice of Standard / Pro / Enterprise based on volume), white-label-friendly access to the underlying infrastructure, and a sub-account API for provisioning your customers as separate tenants on the box. There's no per-customer fee from our side. You're paying for the iron and the operator desk.

The platform you build on top — the customer-facing UI, the campaign builder, the analytics dashboard, the billing system, the support portal — is yours. Most resellers we work with run something based on MailWizz, Mautic, or a custom-built admin panel that connects to our PowerMTA over SMTP relay or our HTTP API. A few use the open-source Mautic ecosystem. One built their entire UI in Vue and pipes everything through our API. We don't have a strong opinion about which one is right; what we care about is that the architecture below it (vMTAs, IP allocation, FBL routing) is correct.

Customer onboarding from your end looks like this: you create a new tenant in our control plane (one API call), assign it dedicated IPs from your pool (you decide how many — typically 2-4 for a starter customer, scaling with volume), generate the DKIM keys, configure the SPF includes, and hand the customer SMTP credentials or an API key scoped to their tenant. The customer's reputation is then isolated — bad behaviour from one tenant doesn't bleed into the others. The Spamhaus listing we've described elsewhere on this site only affects the IPs allocated to that tenant.

The pieces of operator work we do that you don't: daily DNSBL sweeps across all 50+ lists for every IP allocated to your customers, FBL ingestion from Yahoo, AOL, Hotmail, Microsoft 365, La Poste, and Comcast (per IP, routed back to the originating tenant), SBL/CSS remediation when something does list, hardware replacement when a server fails, OS patching, PowerMTA version upgrades. None of these are visible to your customer; they just see "the platform works." That invisibility is what you're paying us for.

Pricing scales with infrastructure: as your customer book grows past what one Pro server can carry (roughly 200 active customers depending on their volume distribution, or 150K msg/hr aggregate), we either add a second box for an Enterprise upgrade, or split the customer book across two boxes for redundancy. The decision usually has more to do with the shape of your traffic than the absolute number — one customer doing 100M/mo is very different from a hundred customers averaging 1M each, even though the totals match.