Hi JPrino,
I don't think you need to buy an Exchange server just to send email using an application \device.
Try these options:
*Internet Information Server (IIS) for relay (Windows Server)
*Send email using Office 365
https://technet.microsoft.com/en-us/library/dn554323(v=exchg.150).aspx
* Gmail SMTP relay(Free or GoogleApps)
https://support.google.com/a/answer/2956491?hl=en
Please note the options would slightly change, depending on HP 9250c Digital Sender capability to authenticate or not.
Using smtp.gmail.com with HP digital sender 9250c:
Hi JPrino,
Do come back and update us on the result. This would help us close the issue.