How can PHP configuration settings, such as php.ini or sendmail, affect the functionality of the mail() function?

PHP configuration settings such as php.ini or sendmail can affect the functionality of the mail() function by determining how emails are processed and sent. For example, if the sendmail_path in php.ini is not properly configured, the mail() function may not be able to send emails. To resolve this issue, ensure that the sendmail_path is correctly set in php.ini and that the sendmail service is properly configured on the server.

// Example of setting the sendmail_path in php.ini
ini_set('sendmail_path', '/usr/sbin/sendmail -t -i');