For agencies running client domains

An agency doesn’t have one email problem. It has one email problem per client, and then one more for itself. The design studio needs hello@ on its own domain, the retainer client wants press@ and jobs@ on theirs, the newest project just bought a domain at a registrar nobody remembers the login for — and every one of those domains is currently a separate account, a separate bill, and a separate place mail goes to die.

SuperMailOS collapses all of it. Every domain you run — yours and your clients’ — lives in one inbox, on one bill. Add a client’s domain, hand out the addresses they need, and read everything in one place instead of tab-hopping between three providers and two webmail logins.

Aliases that outlive your staff roster

Client work has churn built in. The account manager who owned social@client.com leaves; the intern who watched pr@ graduates. With per-address pricing, every one of those changes is a billing event. With SuperMailOS, it isn’t: aliases are unlimited and free, because you pay for people, not addresses.

That means the sensible agency setup costs nothing extra. Keep a real mailbox for every human who handles mail, and give every function — newbusiness@, press@, jobs@, invoices@ — an alias that forwards to whoever currently owns it. When the roster changes, you repoint an alias. The address your clients’ customers learned to trust never changes.

Deliverability on domains you don’t control

Here’s the part that quietly hurts agencies. You can write a perfect campaign for a client, but if SPF, DKIM, and DMARC aren’t right on their domain, the mail soft-lands in spam and the client blames the agency. And most clients cannot tell you where their DNS is hosted, let alone add a TXT record.

SuperMailOS manages that for every domain you add. The authentication records are generated for you, IP reputation and warmup are handled on the sending side, and a live deliverability dashboard shows how mail is actually placing — per domain, so you can see which client’s domain needs attention before they ask. If the client’s DNS is on Cloudflare or DigitalOcean, setup is one-click; anywhere else, you get a short guided list of records to paste. Either way, a new client domain takes under five minutes.

One bill the finance person can actually read

Agencies get priced out of the big suites not by mailboxes but by arithmetic: per-user fees times per-client domains times staff churn. SuperMailOS bills per person, full stop. Pro covers up to 3 domains at $4 per mailbox per month ($3 billed annually) — enough for your own domain plus a couple of client projects. Business, at $6/$5, is unlimited domains, which is the plan that fits an agency whose client list keeps growing.

The inbox itself is familiar on purpose: threaded, Gmail-like, with IMAP and SMTP if someone on the team lives in a desktop client. Nobody needs a training session, which matters when the person checking client mail this month is not the person who checked it last month.

What it looks like in practice

• Onboard a new client in minutes: add their domain, one-click or guided DNS, create hello@ and the role aliases, done before the kickoff call ends.
• Reassign work without touching addresses:aliases point at people; people change; addresses don’t.
• Prove mail is landing: the deliverability dashboard is per-domain evidence you can screenshot into a client update.
• Keep client and studio mail separate but visible: every domain, one inbox, no domain’s mail buried.

Try it on your own domain first — the 14-day trial needs no card. Add one client domain, watch it deliver, and see why mail lands in spam become someone else’s problem. If you want the fuller comparison against the suites you’re currently paying for, we wrote one honestly.