Troubleshooting PHPMailer SMTP Connections in Hosted Environments

The donor described a familiar PHPMailer error:

SMTP -> ERROR: Failed to connect to server: Network is unreachable (101)

The original note also referenced common SMTP hosts and ports such as smtp.yandex.ru, smtp.gmail.com, and ports 25, 465, and 587.

What to verify first

• the host and port are correct for the chosen provider
• the expected encryption mode matches the port
• the server can actually reach the provider over the network
• firewall or hosting restrictions are not blocking outbound SMTP

The key point is that PHPMailer can only report what the transport layer allows. If the network cannot reach the SMTP service, no amount of application-side tweaking will fix the connection.