php发送邮件函数，支持html和普通文本

<?php
function send_mail($emailaddress, $fromaddress, $namefrom, $emailsubject, $body)
{
  $eol="\n";
  $mime_boundary=md5(time());
   
  # Common Headers
  $headers .= "From: $namefrom <$fromaddress>".$eol;
  $headers .= "Reply-To: $namefrom <$fromaddress>".$eol;
  $headers .= "Return-Path: $namefrom <$fromaddress>".$eol;
            // these two to set reply address
 $headers .= "Message-ID: <".$now." TheSystem@".$_SERVER[&#39;SERVER_NAME&#39;].">".$eol;
 $headers .= "X-Mailer: PHP v".phpversion().$eol;          // These two to help avoid spam-filters
   
  # Boundry for marking the split & Multitype Headers
  $headers .= &#39;MIME-Version: 1.0&#39;.$eol;
  $headers .= "Content-Type: multipart/related; boundary=\"".$mime_boundary."\"".$eol;
   
  $msg = "";    
   
   
  # Setup for text OR html
  $msg .= "Content-Type: multipart/alternative".$eol;
   
  # Text Version
  $msg .= "--".$mime_boundary.$eol;
  $msg .= "Content-Type: text/plain; charset=iso-8859-1".$eol;
  $msg .= "Content-Transfer-Encoding: 8bit".$eol;
  $msg .= strip_tags(str_replace("<br>", "\n", $body)).$eol.$eol;
   
  # HTML Version
  $msg .= "--".$mime_boundary.$eol;
  $msg .= "Content-Type: text/html; charset=iso-8859-1".$eol;
  $msg .= "Content-Transfer-Encoding: 8bit".$eol;
  $msg .= $body.$eol.$eol;
   
  # Finished
  $msg .= "--".$mime_boundary."--".$eol.$eol;  // finish with two eol&#39;s for better security. see Injection.
   
  # SEND THE EMAIL
 // ini_set(sendmail_from,$fromaddress);  // the INI lines are to force the From Address to be used !
  mail($emailaddress, $emailsubject, $msg, $headers);
   
//  ini_restore(sendmail_from);
//  echo "mail send";
    return 1;
}
   
?>