Johnny,

Is your printer sending alerts to local users or email addresses on the Internet? If alerts are sent to local users - meaning destined for domains that are configured in Xeams as local domains, you don't need to do anything. Simply specify Xeams host name/IP address in the printer's SMTP server.

If you need to send alerts to foreign domains, such as gmail.com or hotmail.com, you will have to add printer's IP address for relaying. Xeams will not accept out-bound emails unless you use SMTP Authentication or the IP address is among the relaying list. Since you cannot use SMTP Auth, the only option left is accepting relaying from the IP address of your printer. You can even use a wildcard address like 192.168.1.* .

A Potential Problem

Since you're using Xeams on QNAP, there could be another potential issue. There are two packages for Xeams on QNAP: one that you download from QNAP's website and another you download from Xeams.com (http://xeams.com/XeamsDownload.htm). The QNAP's package runs Xeams within Container Station that creates a semi-vitirual machine within QNAP. As a result, every email coming in to Xeams appears to come from a local LAN ip that looks something like 10.0.0.x. Therefore, allowing relay from this IP inadvertently opens up your entire Xeams as an open relay. 

Therefore, we recommend you don't QNAP package from our website rather than running it within Contain Station.