SMTP connection failed: cannot connect to mail server

Incorrect SMTP server hostname or IP address configured in the email properties. The server name may be misspelled or the IP address may be outdated. (high likelihood)

Wrong SMTP port number specified in the configuration. Common ports are 25, 465, or 587, and using the incorrect port will prevent connection. (high likelihood)

Firewall or network security blocking outbound connections on the SMTP port. Corporate firewalls often block port 25 or require specific whitelist entries. (medium likelihood)

TLS/SSL encryption settings mismatch between ServiceNow and the mail server. The server may require encryption while ServiceNow is configured for plain text or vice versa. (medium likelihood)

Mail server is temporarily unavailable or experiencing downtime. The SMTP service may be stopped or the server may be undergoing maintenance. (low likelihood)

Step 1: Navigate to System Properties > Email and verify the SMTP server hostname or IP address in the glide.smtp.server property matches your organization's mail server configuration.

Step 2: Check the SMTP port setting in glide.smtp.port property and confirm it matches your mail server requirements (typically 25, 465 for SSL, or 587 for STARTTLS).

Step 3: Test connectivity from the ServiceNow instance by going to System Diagnostics > Connectivity Tests and create a new test to your SMTP server on the configured port.

Step 4: Review the TLS/SSL settings by checking glide.smtp.ssl_enable and glide.smtp.starttls_enable properties to ensure they match your mail server's encryption requirements.

Step 5: Verify network connectivity by contacting your network administrator to confirm that outbound traffic on your SMTP port is allowed from the ServiceNow instance IP addresses.

Step 6: Test the email configuration by navigating to System Notification > Email > Test Email Configuration and sending a test message to validate the complete email flow.

Step 7: Check the System Log at System Diagnostics > Log > Application Log for any additional error details that might indicate authentication failures or protocol-specific issues.

Step 8: If using an external SMTP service like Office 365 or Gmail, verify that the service is operational and check for any service-specific authentication requirements or IP whitelist needs.