I'm all of a sudden getting the following errors when trying to send email. Some emails send fine, others don't. I have over 1K emails stacked up in my mail tasks

My email config in Lucee is:

When I try to send a test message for this smtp server, Lucee indicates that the task succeeds with the message: "Test mail has been sent successfully using [ email-smtp.us-east-1.amazonaws.com ]." but the message does not get delivered. The undelivered mail does show up in tasks, and fails again when I try to execute the task manually.

An aside, the problem very specifically started on Oct. 2, which may have coincided with my last Lucee update, but I cannot recall the exact date that I updated so I cannot confirm that the update was the problem. Is there a way for me to determine the last time Lucee was updated to determine if the update caused the problem?