Function To Avoid Email Injection

function spamcheck($field)
  {
  //filter_var() sanitizes the e-mail
  //address using FILTER_SANITIZE_EMAIL
  $field=filter_var($field, FILTER_SANITIZE_EMAIL);

  //filter_var() validates the e-mail
  //address using FILTER_VALIDATE_EMAIL
  if(filter_var($field, FILTER_VALIDATE_EMAIL))
    {
    return TRUE;
    }
  else
    {
    return FALSE;
    }
  }

In the code above we use PHP filters to validate input:

• The FILTER_SANITIZE_EMAIL filter removes all illegal e-mail characters from a string
• The FILTER_VALIDATE_EMAIL filter validates value as an e-mail address