Thanks for your response. I have already confirmed that this setting is on and has always been on in Sign-in & Security. When I test, the problem still persists. Below is my config.default.php [username & password redacted].I am baffled by this issue. Thanks!
Use an external SMTP server for outgoing emails (e.g. Gmail).
$smtp_secure='tls'; # '', 'tls' or 'ssl'. For Gmail, 'tls' or 'ssl' is required.
$smtp_host='smtp.gmail.com'; # Hostname, e.g. 'smtp.gmail.com'.
$smtp_port=587; # Port number, e.g. 465 for Gmail using SSL.
$smtp_auth=true; # Send credentials to SMTP server (false to use anonymous access)
$firstname.lastname@example.org'; # Username (full email address).
$smtp_password='A***********5'; # Password.