NPM can monitor the network bandwidth utilization of your devices, interfaces, and applications using SNMP and NetFlow protocols. Network bandwidth utilization is the amount of data transmitted or received over a network link in a given time period. High network bandwidth utilization can indicate network congestion, packet loss, latency, or other performance issues that can affect the email delivery speed. By looking at the network bandwidth utilization of the devices and interfaces involved in the email communication, you can identify the possible bottlenecks or sources of network problems that might be causing the email slowness.  References :  Monitor network bandwidth utilization in NPM ,  Network Bandwidth Analyzer Pack ,  How to Monitor Network Bandwidth Using the Command Line .

 The Universal Device Poller (UnDP) is a feature that allows users to create custom monitors for almost any statistic provided by SNMP based on its Management Information Base (MIB) and object identifier (OID). However, sometimes the OID that the user wants to monitor may not be available in the MIB tree, either because it is not supported by the device or because the MIB database is outdated. In this case, the user needs to update the MIB database to get the latest MIBs from the SolarWinds website or from the device vendor.  This will ensure that the UnDP can find the OID in the MIB tree and poll it successfully 1 2 .  References :  1 : Update the SolarWinds MIB Database for the SolarWinds Platform 3 ,  2 : Monitor custom statistics based on OIDs with Universal Device Pollers in the SolarWinds Platform https://documentation.solarwinds.com/en/success_center/orionplatform/content/core-downloading-the-solarwinds-mib-database-sw3581.htm

 If you do not want to be notified when an interface is down, you can specify that the interface is unpluggable. The interface status is not reflected in the status of the parent node and in alerts. On the Node Management view, select the interface, and click Edit Properties. Select Display Interface as Unplugged Rather Than Down, and click Submit.  The interface status does not influence the status of the parent node 1 .  References :

Suspend collecting data for interfaces in NPM - SolarWinds  (see the Set the interface status as Unpluggable section)