Hi Rick,
I've been trolling through my logs since we went to a 2 server load-balanced environment and I've been seeing a fair number of these errors. My initial research indicates this is related to SMTP. I understand this is a rather vague start to the conversation, but while I continue my research I figure it doesn't hurt to share with you to see if you have any thoughts.
Thanks!

And I've asked my DeVops folk to verify the TLS protocols enabled on the servers. I've been told that only 1.2 & 1.3 are enabled. I'm using .Net mode but not explicitly setting lUseSSL or the port. Perhaps therein lies the rub?
If you're sending email you need to definitely specify nPort
and lUseSsl
unless you're using non-secure and default SMTP port (32). Both are pretty unlikely these days unless you have an internal mail server behind a firewall (also unlikely).
+++ Rick ---
Thanks, Rick.
Our servers live inside our network and we are using a private route to our SMTP provider. Having said that I'll look into using SSL, etc and see if those errors are eliminated.
Key is to check what port and protocols are used by the Mail Server. If you're using an internal server nothing should have changed there?
+++ Rick ---

The one significant change is that on the old singleton server I was using IIS 6.0 SMTP service to forward to our external SMTP provider. Every time I tried to configure that on these new servers, it crashed. So I just pointed to the external service and since things seemed to work I moved on. Too soon apparently...