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Running a small business often means using what you already have.Your website might sit on Hostinger with its free mailbox, while your team wants Microsoft 365 for Outlook, Teams and calendars.
The good news is that you do not need to choose one or the other. With a split email setup you can use Microsoft 365 and Hostinger email on the same domain.
Some mailboxes live in Microsoft 365, others stay in Hostinger, and everything still works with one clean address like name@yourdomain.com.
What “Split Email” Between Microsoft 365 and Hostinger Actually Means
In a typical setup your domain has one mail provider. All email goes to that provider’s servers and is delivered there.
Split email is different.
You tell the internet to send all incoming mail to Microsoft 365 first. Microsoft then checks if the mailbox exists in Exchange Online:
- If the mailbox exists in Microsoft 365, the message stays there.
- If the mailbox does not exist, Microsoft forwards it to another system – in this case, Hostinger.
This is called an internal relay domain in Exchange Online. You also create a connector from Microsoft 365 to Hostinger. The connector is just a safe route that says, “for unknown users on this domain, relay mail to mx1.hostinger.com and mx2.hostinger.com”.
The result:
- Your main users (for example management and sales) enjoy full Microsoft 365 features.
- Generic addresses like info@ or support@ can stay on Hostinger’s simple webmail.
- You keep one brand and one domain everywhere.
Step-by-Step: Sharing One Domain Between Microsoft 365 and Hostinger
- Verify your domain in Microsoft 365
Add the TXT record Microsoft gives you in your Hostinger DNS panel.
Once Microsoft sees it, the domain shows as verified.
- Point the MX record to Microsoft 365
In Hostinger DNS, delete the old Hostinger MX records.
Add a single MX that points to
mail.protection.outlook.com with priority 0. From now on, every incoming message reaches Microsoft 365 first. - Fix SPF so both systems can send mail
You should have only one SPF TXT record for the root of the domain.
Use a combined value such as:
v=spf1 include:_spf.mail.hostinger.com include:spf.protection.outlook.com ~all
This tells other servers that mail from both Hostinger and Microsoft 365 is valid.
- Set the domain to Internal Relay in Exchange
In the Exchange admin centre, open Mail flow → Accepted domains.
Edit your domain and change the type from Authoritative to Internal relay.
This is what allows Microsoft 365 to forward mail instead of bouncing it.
5. Create the connector from Microsoft 365 to Hostinger
Still in Exchange, go to Mail flow → Connectors and create a new connector:
- From Office 365 to Partner organisation.
- Use it only when sending to your domain.
- Route mail via smart hosts mx1.hostinger.com and mx2.hostinger.com.
- Require TLS and allow any valid certificate.
- Choose which addresses live where
- Create Microsoft 365 users for addresses you want in Outlook, such as yourname@domain.
- Leave addresses like info@domain or support@domain only in Hostinger Email. Do not create the same mailbox in both places.
- Test from an external account
Use a Gmail address and send test messages:
- To an M365 mailbox → it should appear in Outlook.
To a Hostinger-only mailbox → it should appear in Hostinger webmail. If both work, your split email setup is live.
Splitting email between Microsoft 365 and Hostinger might look technical at first, but once it is in place it works quietly in the background. Your team can enjoy Outlook and Teams, while simple mailboxes stay on low-cost hosting, all under one trusted domain name. If you plan your addresses carefully and test each route, this setup gives you a flexible, future-proof email system without forcing you to move everything in one big migration.