Spamtitan appliance

Hi,

We are having 2 VMs running Spamtitan and they provides us the snmp to read to have some stats.

In addition the following OIDs provide information on the size of the mail queues:

.1.3.6.1.4.1.2021.8.1.101.1 - Active Queue
.1.3.6.1.4.1.2021.8.1.101.2 - Incoming Queue
.1.3.6.1.4.1.2021.8.1.101.3 - Deferred Queue
.1.3.6.1.4.1.2021.8.1.101.4 - Corrupt Queue
.1.3.6.1.4.1.2021.8.1.101.5 - Hold Queue

(Imported from https://github.com/librenms/librenms/issues/8886, Original request by: @PointPubMedia)