Setting up GFI FaxMaker with Microsoft Office 365 Enterprise Accounts

Overview

GFI FaxMaker can be configured to work with Microsoft Office 365 Enterprise accounts. This article provides the configuration steps.

Information

GFI FaxMaker must be installed and ready to be configured with Microsoft Office 365 Enterprise accounts. For more information, refer to Installing or Upgrading GFI FaxMaker.

Process

Setting up GFI FaxMaker with Microsoft Office 365 Enterprise accounts involves two main steps:

Setting the mail server details.
Setting the connectors.

Step 1: Set the Mail Server Details

On completion of the GFI FaxMaker installation, the installer automatically launches the Configuration Wizard that assists you through the basic steps of configuration. Configure the following wizard steps:

In the Configuration Wizard welcome screen click Next.

Choose My email server will forward faxes and SMSs to this GFI FaxMaker machine. Click Next and complete the following options:

Option	Description
Mail server name or IP address	Key in `smtp.office365.com`.
Port	Key in `587`.
Use Secure Connection	Select this option and choose TLS.
Use SMTP Authentication	Select this option and enter the credentials of a Microsoft® Office 365™ mailbox user. Key in the user's full email address in the Account name and the Password. Do not select Secure Password Authentication. Recommended for FaxMaker 20.9 and later: use Office365 Authentication (OAuth 2.0) instead of a password. Microsoft has announced that password-based SMTP AUTH will be disabled by default for existing tenants at the end of December 2026.

Figure 1: Mail server configuration options

NOTE: If GFI FaxMaker is already installed, configure the above mail server details from GFI FaxMaker Configuration > Email2FaxGateway.

Proceed with the wizard to finalize the configuration.

NOTE: When sending emails to your organization users, for example when notifying administrators of system errors, GFI FaxMaker sends the email from the email address fax@<fax domain> domain (e.g., fax@faxmaker.com). Ensure that GFI FaxMaker can send emails via your mail server from this email address.

Recommended: Office365 Authentication (OAuth 2.0)

The SMTP Connector can sign in to Microsoft 365 with OAuth 2.0 instead of a password. This option was added in FaxMaker 20.8. Use FaxMaker 20.9 or later (the latest version is recommended), because the 20.8 build has a known web interface issue described in the GFI FaxMaker 20.8 release notes. Microsoft has announced that password-based (Basic) SMTP AUTH will be disabled by default for existing tenants at the end of December 2026: Updated Exchange Online SMTP AUTH Basic Authentication Deprecation Timeline.

A. Register an app in Microsoft Entra ID

In the Microsoft Entra admin center, go to App registrations > New registration.
Enter a name and set Supported account types to Accounts in any organizational directory (Multitenant). Click Register and note the Application (client) ID.
Go to API permissions > Add a permission > Microsoft Graph > Delegated permissions. Add SMTP.Send and offline_access, click Add permissions, then click Grant admin consent.
Go to Authentication > Add a platform > Mobile and desktop applications and add the redirect URI http://localhost:5000/callback.
Under Advanced settings, set Allow public client flows to Yes and click Save.

NOTE: The redirect URI must be added under Mobile and desktop applications, not Web. Otherwise FaxMaker cannot keep its sign-in token. See Fix: GFI FaxMaker “Office 365 Authentication” (OAuth) Fails for Email2FaxGateway.

B. Prepare the sending mailbox

Choose a licensed Microsoft 365 mailbox for FaxMaker to send from. In the Microsoft 365 admin center, go to Users > Active users, select the user, open Mail > Manage email apps and make sure Authenticated SMTP is selected.

C. Check connectivity from the FaxMaker server

Run these commands in PowerShell on the FaxMaker server and confirm both succeed:

Test-NetConnection login.microsoftonline.com -Port 443
Test-NetConnection smtp.office365.com -Port 587

D. Configure the SMTP Connector

In GFI FaxMaker Configuration, right-click Email2FAXGateway, select Properties and open the SMTP Connector tab.
Select Office365 Authentication and enter:
- Mail server name/IP: smtp.office365.com, port 587
- Mailbox account: the mailbox from step B
- Authorization redirect URL: http://localhost:5000/callback
- Timeout (in minutes): 1 or more
- Client ID: the Application (client) ID from step A
Click Authenticate and sign in as the mailbox in the browser window that opens. When sign-in completes, you can close the browser.
Enter a test address and click Send test email.
Click OK. Close and reopen GFI FaxMaker Configuration and confirm that Office365 Authentication is still selected.

E. Confirm real fax email delivery

With Office365 Authentication, Send test email is sent from the signed-in mailbox. Received faxes, transmission reports and notifications use the fax domain address (by default fax@faxmaker.com) as the SMTP sender, so a successful test email does not confirm that these emails will be delivered. After the test email succeeds:

Send a fax to a FaxMaker line and confirm it arrives in the recipient's mailbox.
Send an outbound fax and confirm the transmission report reaches the sender.
If either email does not arrive, check smtpin.fmlogger.txt as described in smtpin.fmlogger.txt Log File Shows Failed Attempts to Upload Email. If the error contains SendAsDenied, see Receiving Sendasdenied Error Sending Faxes From Office 365.

Step 2: Set the Connectors

NOTE: Connectors are not available with all Office 365 plans. If your plan does not support connectors, refer to Microsoft Office 365 Email only accounts.

Configure fax and SMS connectors in Microsoft® Office 365 Exchange Admin Center to route outgoing fax/SMS emails from Microsoft® Office 365 to the GFI FaxMaker server.

Connectors must be configured such that when the recipient domain of an outgoing email matches the fax or SMS domains, the email gets routed to GFI FaxMaker for fax/SMS transmission.

Create a connector using the following options:

From Office 365.
To your organization’s email server.
Choose to use the connectors when email messages are sent to particular domains and add the fax and SMS domains.
Specify the GFI FaxMaker server public IP address or Fully Qualified Domain Name as the Smart Host.

Configure the other connector settings depending on your organization's setup. For more information refer to the Microsoft article Configure mail flow using connectors in Office 365.

Your users should now be able to send faxes using the standard addressing format <fax number>@faxmaker.com (for example, 12345678@faxmaker.com).

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Confirmation

Test fax sending:

Use a hosted email user to send a fax or SMS via email.
View the email being processed in the GFI FaxMaker Monitor and confirm that the fax is received by the recipient.
If you cannot see the fax email being processed in the GFI FaxMaker Monitor, troubleshoot the relaying of the email from the mail server to GFI FaxMaker.

Test fax receiving:

From a test fax line, send a fax to a fax line connected and configured in GFI FaxMaker.
View the incoming fax status from GFI FaxMaker Monitor.
Unless Routing rules were previously configured, the fax is delivered through the Default Routers (Available from GFI FaxMaker Configuration > Routing > Properties > Default Routers). Ensure that the fax is successfully delivered to the Default Routers’ mailbox.