In what scenarios should the set_crlf() function be used in PHP email sending to prevent formatting errors?

When sending emails using PHP, the set_crlf() function should be used to prevent formatting errors when dealing with different line endings. This function sets the email line ending to CRLF (Carriage Return Line Feed) which is the standard for email headers and content. By using set_crlf(), you ensure that your emails are formatted correctly across different email clients and servers.

// Set the email line ending to CRLF
mail_set_crlf("\r\n");

// Send the email
mail($to, $subject, $message, $headers);