Below are the steps that can help you configure Helpdesk Pilot to use Exchange Server Mailbox as your Outgoing Mail Server. 

Please Note: The screenshots and steps below based on Exchange Server 2010 SBS Edition. Some of the screenshots and steps might slightly vary depending on the Exchange Server version and edition that you are using.

1. From your Exchange Server computer, open Exchange Management Console. In the Exchange Management Console, navigate to Microsoft Exchange Server > Microsoft Exchange On-Premises >  Organization Configuration > Server Configuration > Hub Transport. 
2. In the right-bottom you will see a list of Receive Connectors that has been already configured in your Exchange. 
3. Right click on empty space on the Receive Connectors list and choose New Receive Connector... from the context menu which will open New Receive Connector wizard. 
4. Specify the Name as HDP Relay and select Custom from Select the intended use for this Receive Connector drop down as shown below and Click Next.
   
5. On the Local Server Settings wizard page, accept the default settings and click Next.
6. On the Remote Server Settings wizard page, select 0.0.0.0-255.255.255.255 and click Edit to open the Edit Remote Server Settings - IP Address Range dialog. Specify your Helpdesk Pilot server IP Address in both Start Address: and End Address:
    
7. Important Note: Please note, you give you only one IP address in the above dialog which is definitely the Helpdesk Pilot server IP Address. 
8. Click OK to save settings and close the dialog and click Next.
9. Click on New on New Connector wizard page and once completed click on Finish to close the dialog.
10. From the Receive Connectors list, double click on HDP Relay to modify the properties. 
11. In the Permissions Groups tab of the HDP Relay Properties dialog, check all the five checkboxes as shown below.
     
12. In the Authentication tab of HDP Relay Properties dialog, check Transport Layer Security (TLS) and Externally Secured (for example, IPSec) option and uncheck all other checkboxes from the Authentication tab as shown below.
     
13. Click OK to save the HDP Relay Properties settings. With this step, Exchange Server configuration is done. 
14. Open Helpdesk Pilot Staff Panel and login as account administrator to modify Outgoing EMail Settings in Helpdesk Pilot. 
15. Once logged in, goto Manage > General and scroll down to view Outgoing EMail Settings as shown below.
     
16. Specify an email address in the From Address which is a valid mailbox in your Exchange Server.
17. Select Use External Mail Server option from the SMTP Server drop down. Once selected, you will get additional options.
18. Fill in your SMTP Host Name as your Exchange Server IP Address or if your exchange server has a domain name associated, you can specify the host name as your domain name.
19. Select No for SSL drop down and specify the Port Number for your Exchange SMTP Server. 
20. Now your Outgoing EMail Settings might look something like this.
     
21. Now click Save Settings to save the settings done above. We will do a Test Connection once we complete the configuration on the Microsoft Exchange Server.
22. Now go to Helpdesk Pilot's Outgoing EMail Settings and click on Test Connection to validate and check the settings done above. This test should be successful, if not please revisit the steps above to check if any of the above settings has been missed.
23. Once the Test Connection is successful, you can go to the Troubleshooting link at the right of your Helpdesk Pilot screen.