ITFlow must be configured with your mail server settings to send outbound emails for things such as ticket notifications and invoices.
Configure at Settings > Mail:
Make sure your SMTP is enabled for your account (ask your provider to check, if you don't have admin access)
Open the Microsoft 365 admin center and go to Users > Active users.
Select the user, and in the flyout that appears, click Mail.
In the Email apps section, click Manage email apps.
Verify the Authenticated SMTP setting: unchecked = disabled, checked = enabled.
When you're finished, click Save changes.
Generating an app password requires MFA.
Go to the Security basics page and sign in to your Microsoft account (aka.ms/MFASetup).
Select More security options.
Under App passwords, select Create a new app password. A new app password is generated and appears on your screen.
Enter this app password where you would enter your normal Microsoft account password in the application.