ipmonitor not sending smtps alerts

I'm running ipMonitor 11 on Windows Server 2016, and I cannot seem to get the e-mail alert to work over SMTP SSL, port 465.

From the server, I can verified it can connect to our internal e-mail server over port 465.

The e-mail server is an iredmail server.  It is showing an error: "SASL PLAIN authentication failed", which typically means a failed username/password login.  However, I've triple checked the SMTP credentials, and it is working fine on all other software/equipment in our environment.  

Seems as if ipMonitor is not supporting SMTP over SSL/TLS, is this a correct assumption?