SMTP (Simple Mail Transfer Protocol) connections enable applications to send emails reliably. To configure SMTP, you need server details including hostname, port number, and authentication credentials. Common ports include 587 for TLS encryption and 465 for SSL encryption.

Most email providers like Gmail, Outlook, and SendGrid offer SMTP access. When using third-party services, generate app-specific passwords instead of using your main account password. Implement connection pooling to improve performance when sending multiple emails.

Test SMTP connections thoroughly before production deployment. Handle connection errors gracefully with retry mechanisms and appropriate error messages. Monitor email delivery rates and bounce rates to identify issues. Always include proper email headers and respect anti-spam regulations.