Billbee and Microsoft 365 Exchange A practical mail-flow note for sending business e-mails from Billbee.

Like many small business systems, Billbee works very well until one specific setup does not fit the default examples.

In my case, I wanted Billbee to send e-mails via Microsoft 365 Exchange instead of using a classic provider setup such as Strato or IONOS.

The problem

At first, the setup did not work because I interpreted the e-mail settings like a classic SMTP login. With Microsoft 365 and multi-factor authentication, that approach quickly becomes unreliable or impossible.

Classic SMTP confusion

The usual combination of username, password, SMTP server, SSL or TLS did not work as expected.

MFA in the way

Microsoft 365 sign-in through an authenticator app changes the situation. A simple password-based SMTP setup is not the right path here.

Wrong mental model

The solution was not to fight with the old SMTP idea, but to use the Microsoft 365 mail-flow structure properly.

Business need

Billbee still needed to send customer and order e-mails reliably from the business domain.

Finding the MX server

The first useful step was finding the domain's Microsoft Exchange MX record in the Microsoft 365 admin area.

In Microsoft 365, this can be found under admin.microsoft.com, then Settings / Domains, then the selected domain and its DNS records. In the Microsoft Exchange section, the MX record looks similar to mydomain-de01b.mail.protection.outlook.com.

Creating the connector

The key step was creating a connector in the Microsoft 365 Exchange Admin Center under Mail flow / Connectors.

Connector direction

Create a connector for Your organisation's e-mail server.

Name

Use a clear name such as Billbee. A long description is not necessary.

Authentication

Select the option that verifies the sending server by IP address.

Billbee IPs

Enter the IP addresses specified by Billbee. Confirm each IP address with the plus button, otherwise it may not be saved.

Billbee sending settings

After the connector exists, the Billbee e-mail sending configuration needs to match the Microsoft 365 mail-flow setup.

Sender: Microsoft e-mail address or alias
SMTP server: your MX record, for example mydomain-de01b.mail.protection.outlook.com
Port: 25
Login and password: Microsoft 365 credentials
StartTLS: active

The port mattered in this setup. Port 25 was the working choice here; other port numbers did not work.

SPF consideration

To reduce the risk of outgoing messages being treated as suspicious, the SPF record should also reflect the authorised sending path.

v=spf1 ip4:Static-IP-address-from-Billbee include:spf.protection.outlook.com -all

The exact SPF record depends on the real sending setup. Blind copying is not recommended; it should match the actual Billbee IP values and the Microsoft 365 domain configuration.

        Important note

        This is a practical configuration note from one working setup. Microsoft 365, Billbee and DNS settings can change, so the real admin panel should always be checked carefully.

Connector created. Billbee configured. Mail sending via Microsoft 365 worked.

Ask about this note

Mail systems rarely fail politely. They prefer riddles with ports, connectors and DNS records.

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