This blog discusses troubleshooting steps to investigate the failure of SQL Server Database Mail service on sending email. It also discusses 2 special scenarios with SQL Server Database Mail that commonly cause mail sending failure
General Troubleshooting Steps to Narrow Down RCA Special Scenarios:
Scenario 1: Implicit SSL/TLS mode is not supported for SQL Server DB Mail. If your SMTP server requires implicit TLS, then SQL Server DB Mail will not be able to send email using this SMTP server.
Scenario 2: SQL DB Mail failure caused by SMTP mail server requesting TLS 1.2. In this case, TLS