Every domain gets its own inbox. You keep paying for one seat.
inboxroot turns each domain you own into a free mailbox inside the Microsoft 365 or Google Workspace subscription you already have — its own address, its own inbox, its own send identity. Postmark handles transactional mail on the same domains.
Works with your own Microsoft 365, Google Workspace & Postmark · Cancel anytime · No seat per domain
Owning ten domains shouldn't mean paying for ten mailboxes
Everyone who runs more than one brand hits the same wall, and every way around it costs something you didn't want to spend.
Clean, obvious, and the cost scales exactly with your ambition. Ten domains is $60–140 a month for mailboxes that are mostly empty, forever.
Free, but every domain lands in the same inbox. You lose the boundary that made them separate brands, and replies leave from whichever address the client picks.
Mail arrives, but you can't reply as the domain without SMTP relay gymnastics, and forwarded mail routinely fails SPF at the receiving end.
Uses the free primitive both providers already offer — a shared mailbox in Microsoft, a Group inbox in Google — so each domain is genuinely separate and genuinely free.
The part your provider already gives away
There is no trick here worth hiding — just two facts that don't get put next to each other often enough.
Microsoft bills per licence and hosts roughly 900 accepted domains per tenant at no charge. Google bills per user and allows 600 secondary domains on a subscription. Adding a domain has never been the thing you pay for.
Microsoft's shared mailboxes are free under 50 GB. Google's Groups are free without limit. Both can receive at their own address, and both can be granted to a licensed account that then replies as that address.
Per domain that is nine or ten pieces of configuration across two consoles and a registrar, each of which fails quietly. inboxroot does them in order and checks each one landed.
Connect your accounts
Sign in and grant consent once — to Microsoft 365, Google Workspace, or both, plus your Postmark account. Credentials stay encrypted and server-side; nothing reaches the browser.
Add a domain, publish its records
Enter kibipay.com and pick where its mail should land. inboxroot generates every record — MX, DKIM, Return-Path and one merged SPF — and checks them against public DNS until they resolve.
Provision, and it's live
We create the mailbox, grant your seat access and send-as, and confirm both actually took. hello@kibipay.com shows up in the client you already use.
Ten domains cost the same as one. The only line that moves as you add domains is the number of inboxes you have — not the invoice.
Whatever your team already pays for
Connect one host or both, then choose per domain. Nothing here assumes you have picked a side, and mixed estates are normal.
| Microsoft 365 | Google Workspace | Send-only | |
|---|---|---|---|
| What each domain gets | A free shared mailbox | A free Group inbox, or a real user if you want one | A verified sending identity, no inbox |
| Cost per domain | $0 | $0 for a Group · a seat for a real user | $0 |
| Where you read it | Outlook, auto-mounted | Gmail, plus the Groups collaborative inbox | Wherever it already lives |
| Reply as the domain | Send As | Gmail send-as | Via Postmark |
| Touches your MX | Yes — points at Microsoft | Yes — points at Google | Never |
| Good for | Domains you want to live in Outlook | Domains you want to live in Gmail | Domains already hosted elsewhere |
Send-only mode adds exactly two DNS records and never rewrites MX or SPF — a domain already receiving mail keeps receiving it, untouched.
Two kinds of email, kept apart on purpose
The mail you type and the mail your software sends have different failure modes. Deliverability people separate them; inboxroot sets that up by default.
Reputation firewall
A campaign that draws complaints damages the stream it went out on. Bulk mail rides its own Postmark stream, so it can never reach the one your password resets use.
No sending limits to design around
Microsoft and Google cap what a mailbox may send per day. Application mail leaves through Postmark instead, so a launch doesn't get throttled halfway through.
One SPF record, correctly merged
A domain may only publish one SPF line, and a second silently invalidates the first. We generate a single record covering both senders rather than leaving you to merge it.
Built for people who collect domains faster than budget
The pain is identical whether it's client work, side projects or brands — you own more names than you can justify mailboxes for.
A real inbox on every client domain from day one, without a line item per client or a shared password to a free forwarder.
See the setup →Indie hackers & micro-SaaSEvery experiment gets support@ that a human answers and receipts that land in the inbox, before it earns a penny.
Working mail on a parked name is what makes an offer look real — and what stops inbound enquiries going to a catch-all nobody reads.
See the setup →Multi-brand businessesEach trading name answers from itself. Staff keep one login and one client, and reply from the right identity.
See the setup →The whole job, not just the easy half
Native in the client you use
A real shared mailbox in Outlook or a real Group inbox in Gmail — send, receive and reply as that address in the app that's already open.
Your tenant, your account
Everything runs inside your Microsoft, Google and Postmark accounts. inboxroot orchestrates and then gets out of the way — it never becomes the thing your mail depends on.
DNS generated and verified
Every record for the domain, with a live checker that resolves them against public DNS and names the one that's wrong — including the classic ms.example.com mistake.
Transactional and bulk sending
Postmark sender signatures per domain, a broadcast composer with unsubscribe enforcement, and per-domain sending servers when reputations need separating.
Least privilege by default
SSO sign-in, per-tenant isolation, AES-GCM at rest, and an Exchange access policy that confines mail reading to the mailboxes we created.
One console, and an audit trail
Every domain and its status at a glance, a merged inbox across providers, sent-mail search across servers, and a record of every change we made on your behalf.
The things worth asking before you point MX at anything
Is this a loophole that Microsoft or Google will close?
No — it is documented, supported behaviour. Microsoft charges per licence, not per domain, and shared mailboxes under 50 GB have always been free. Google likewise bills per user and puts no charge on secondary domains or Groups. Nothing here is a grey area: everything inboxroot does is something you could do by hand in the admin console, one domain at a time, and plenty of admins already do.
So what am I actually paying you for?
Repetition. Onboarding one domain properly means an accepted domain, an ownership record, MX, DKIM, a merged SPF line, a Return-Path, a mailbox, two permission grants and a send-as identity — and then confirming each of them actually took. That is an unhurried afternoon the first time and a source of quiet mistakes every time after. inboxroot turns it into three steps, and tells you which record is wrong when one is.
Do you read or store my mail?
We read it, on demand, when you open the inbox view — and we store none of it. There is no mail database here. Messages are fetched from Microsoft Graph, the Gmail API or your IMAP server at the moment you look at them, rendered, and forgotten. On the Microsoft side, provisioning also installs an Exchange application access policy that limits us to the mailboxes we created, so the read permission cannot reach the rest of your tenant.
What happens to my existing mail setup?
Nothing, unless you point a domain's MX at a new host — and you only do that for domains you explicitly onboard as Microsoft or Google inboxes. Domains you add in send-only mode get exactly two records, neither of which touches inbound mail: a DKIM key and a pm-bounces CNAME. We never rewrite your MX or your SPF for those.
Why Postmark as well? Can't I just send from Outlook or Gmail?
You can, for mail you type. You should not for mail your software sends. Application email — receipts, password resets, invites — arrives in bursts, gets marked as spam more often, and hits sending limits your provider enforces per mailbox. Keeping it on a separate service with its own DKIM key means a bad campaign can never take down the inbox your customers reply to.
What if I want to leave?
Everything lives in your accounts, not ours. The domains are on your subscription, the mailboxes are in your tenant, the DNS is at your registrar and the Postmark account is yours. Disconnecting inboxroot removes our access and changes nothing about your mail. There is no export to request, because there is nothing of yours here to export.
How many domains can one seat really carry?
Microsoft accepts around 900 domains on a tenant; Google allows 600 on a subscription. Shared mailboxes are free below 50 GB and Google Groups have no per-group charge. In practice the ceiling you hit first is your own attention, not either provider's limit.
Can I use both Microsoft and Google?
Yes, and per domain. Connect either or both, then choose the host each time you add a domain. Agencies inheriting client setups tend to end up with a mixture, and there is no reason to force it into one column.
Free while we're in beta
inboxroot is free during the beta, and beta users keep a founder discount when paid plans arrive. You pay Microsoft or Google exactly what you already pay them, and Postmark for what you send.