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Someone else's stack,sold with a window.
A reseller runs the same open-source pieces we do: Postfix, DNS, a web server. The difference is what happens at 03:00, and who holds the contract.
What you get
The day-to-day is handled. Patching, certificates, and the queue are someone's job, not yours.
A support window exists, and a ticket gets an answer inside it.
Mailboxes are cheap at small numbers, and onboarding is a form.
What it costs
You are usually one of many tenants on shared sending IPs. Reputation is pooled, and one bad neighbour degrades everyone.
The SLA is the reseller's, and the remedy is a credit on next month's invoice.
The person who answers the ticket is not the person with root, and the hand-off between the two is where tickets go to die.
The stack is a product, not a system. When something is wrong, it is wrong for the product.
Where we differ
The node is named, the facility is named, and the backups are in a city you can point at.
Sending can run on a dedicated domain with its own reputation, on request.
S/MIME keys are issued on your domain, installed, and rotated on a schedule.
The reply is signed, and the signer is the operator.
Pick them when
You need a few mailboxes and a website, and the work is genuinely not critical.
A support ticket with a next-day answer is enough for the risk you carry.
Pick us when
Deliverability is a business dependency, not a convenience.
You want the keys, the runbook, and a person whose name is on the pager.
Not sure which one you are?
Open a brief and say what you have today. If the honest answer is that nothing should change, that is a valid result and you will get it in writing.