Follow these steps:

• Create a Office 365 account for business, if you do not already have one setup.
• Verify / Setup a domain to Microsoft 365 and complete their setup process.
• Please visit and login to your Exchange admin centre at https://outlook.office365.com/ecp/

• We will be creating a shared mailbox in Office365 for your WHMCS support department. Please navigate to Recipients > Shared > New
• Then in the popup form enter the details for your new shared Office365 Mailbox. Ensure to click More Options near the bottom, so you can specify the Alias. Add your admin user to the list of users that have permission to view and send mail from this shared mailbox. In this example we have used [email protected] 

• Now that your Support shared mailbox has been created, please ensure that this mailbox has POP support enabled. You can check this selecting the mailbox, click Edit > Mailbox features > POP3: Enabled.

• Return to your Office365 Admin Center and navigate to Users > Active Users

• Here you will see your newly created shared mailbox user. Click on the key icon and reset the password
• Under Setup > Support > Support Departments in WHMCS, create at least one department and configure the email account assigned to it with the POP3 settings like:

• Create a cron job to trigger the /crons/pop.php file every 5 minutes. We have guides on creating a cron job in most web hosting control panels here: https://docs.whmcs.com/Cron_Configuration

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