Diese Funktion ist ein Alias für: imap_headerinfo().
Some example of how to use it:
<?php
    $imap = imap_open("{mail.example.com:143}INBOX", "username", "password");
    $message_count = imap_num_msg($imap);
    for ($i = 1; $i <= $message_count; ++$i) {
        $header = imap_header($imap, $i);
        $body = trim(substr(imap_body($imap, $i), 0, 100));
        $prettydate = date("jS F Y", $header->udate);
        if (isset($header->from[0]->personal)) {
            $personal = $header->from[0]->personal;
        } else {
            $personal = $header->from[0]->mailbox;
        }
        $email = "$personal <{$header->from[0]->mailbox}@{$header->from[0]->host}>";
        echo "On $prettydate, $email said \"$body\".\n";
    }
    imap_close($imap);
?>
My quick and dirty code to decode utf-8 subject :
function decode_utf8($str) {
   preg_match_all("/=\?UTF-8\?B\?([^\?]+)\?=/i",$str, $arr);
        
   for ($i=0;$i<count($arr[1]);$i++){
     $str=ereg_replace(ereg_replace("\?","\?",
              $arr[0][$i]),base64_decode($arr[1][$i]),$str);
   }
        return $str;
}
$subject = decode_utf8($header->subject);
At jeremy at caramiel dot com:
You are wrong, since it will just work if the encoding of the characters is also used in the current context.
There is a reason why it comes with the charset :)
There are way better solutions with imap_mime_header_decode
Here is a clean way to decode encoded imap headers that will work in all cases :
function fix_text($str)
{
    $subject = '';
    $subject_array = imap_mime_header_decode($str);
    foreach ($subject_array AS $obj)
        $subject .= rtrim($obj->text, "\t");
    return $subject;
}
A simple way to fix encoded subject/from header problem and strip whitespace:
<?php
function fix_text($var){
if(ereg("=\?.{0,}\?[Bb]\?",$var)){
$var = split("=\?.{0,}\?[Bb]\?",$var);
while(list($key,$value)=each($var)){
if(ereg("\?=",$value)){
$arrTemp=split("\?=",$value);
$arrTemp[0]=base64_decode($arrTemp[0]);
$var[$key]=join("",$arrTemp);
}}
$var=join("",$var);
} 
if(ereg("=\?.{0,}\?Q\?",$var)){
$var = quoted_printable_decode($var);
$var = ereg_replace("=\?.{0,}\?[Qq]\?","",$var);
$var = ereg_replace("\?=","",$var);
}
return trim($var);
}
?>
Ex.
<?php
//For =?iso-8859-1?Q Problem
echo $title;
//show: =?iso-8859-1?Q?Boletim:_Motiva=E7=E3o
//,_Gest=E3o_&_Vendas_-_Gilcl=E9r_Regi?= 
//=?iso-8859-1?Q?na?=
echo fix_text($title);
//show: na?
?>
To convert date format from mail header to dd/mm/yyyy H:i use this :
<?
$tgl1 = strtotime($msg->date); //convert to timestamp
$tgl2 = date("d/m/Y H:i",$tgl1); //format date from timestamp
echo $tgl2;
?>
hope this help :)
if you need to grab other fields that are not parsed out by imap_header then use
imap_fetchheader to retrieve the entire email header and do the work yourself.
I just wanted to state what all these variables were producing considering it isnt documented anywhere that I have been able to find on this site:
the object that imap_mailboxmsgs returns has the following fields for the pop3 driver:
array(
     Unread => 
     Deleted =>
     Nmsgs =>  
     Size=>      
     Date=>     
     Driver=>   
     Mailbox=> 
     Recent=>
)
imap_header returns the following array for the pop3 driver:
stdClass Object (
    date=>
    Date=>
    subject=>
    Subject=>
    toaddress=>
    to=> array stdClass Object (
        mailbox=>
        host=>
     )
    fromaddress=>
    from=> array stdClass Object (
        personal=>
        mailbox=>
        host=>
    )
    reply_toaddress=>
    reply_to=> array stdClass Object (
        personal=>
        mailbox=>
        host=>
    )
    senderaddress=>
    sender => array stdClass Object (
        personal=>
        mailbox=>
        host=>
    )
    Recent=>
    Unseen=>
    Flagged=>
    Answered=>
    Deleted=>
    Draft=>
    Msgno=>
    MailDate=>
    Size=>
    udate=>
)
Also, if you are using a pop3 server and you are having difficulties deleting messages, you will need to call imap_expunge immediately after your call to imap_delete. (this was posted somewhere else..  thanks for that!!)
feel free to drop me a line if this helped you.  Happy coding.
A way to print your own specified date:
$date = date('d F Y (G:i:s)',
strtotime(strip_tags($headerinfo->udate)));
It is explained else where on the site but something I struggled with.
To find the size of a message use:
$sizefeed1 = imap_fetchstructure($feed,$messagenumber);
$sizefeed2 = $sizefeed1->bytes;
$size = "$sizefeed2 bytes";
I've got a problem when facing some encoded subject or from header like:
=?big5?B?uXG4o7ZXpEg3MTEw?= or
=?iso-8859-1?Q?A7=EB=B2=BC=B6=7D=A9l=21?=
this problem only appears when the poster is using non-Misco$oft reader, and i lastly find the way to solve.
For the =?big5?B?, the encode method is base64, so you can use base64_decode to decode it to the original one, you can use the following to check and decode:
<?php
if(ereg("=\?.{0,}\?[Bb]\?",$strHead)){
  $arrHead=split("=\?.{0,}\?[Bb]\?",$strHead);
  while(list($key,$value)=each($arrHead)){
    if(ereg("\?=",$value)){
      $arrTemp=split("\?=",$value);
      $arrTemp[0]=base64_decode($arrTemp[0]);
      $arrHead[$key]=join("",$arrTemp);
    }
  }
  $strHead=join("",$arrHead);
}
?>
For =?iso-8859-1?Q?, it uses quoted printable to encode, you can use quoted_printable_decode to decode, example:
<?php
if(ereg("=\?.{0,}\?Q\?",$strHead)){
  $strHead=quoted_printable_decode($strHead);
  $strHead=ereg_replace("=\?.{0,}\?[Qq]\?","",$strHead);
  $strHead=ereg_replace("\?=","",$strHead);
}
?>
Yes, the ref. is quit confusing (to me at least). It will be wise (after spent many hours) to test the type of variable first before it disappointe you. I find $header->From retrurns String, $header->from returns array and its elements are object. Therefore if you want get sender's name for example,
you need: $from = $header->from;
    
        if (is_array($from)){
        
        while(list($key, $val) = each($from)) {
        
        echo $from[0]->personal;
        echo $from[0]->adl;
        echo $from[0]->mailbox;
        echo $from[0]->host;
        }
        }
you will find $header_from is an one element array and this element is an object. Hope anyone else will not wast time here to figure out why retrun is empty.