use strict;
use IO::File;
use Mail::Message::Attachment::Stripper;

# load the mail message into $mail
# extract user folder path into $user_folder
...

my $m = Mail::Message::Attachment::Stripper->new($mail);
my @attachments = $m->attachments;

foreach my $a(@attachments) {
  next if $a->{content_type} !~ /jpe?g|gif/i; # ignore non-jpg/gif att
+achemnts
  my $f = new IO::File "/home/$user_folder/" . $a->{filename}, "w" or
     die "Can not create file!";
  print $f $a->{payload};
}
[download]

This might be a good place to start.

You don't mention which mailserver you're running but you'll probably want to use procmail at some point although you sound like you want to deal with the attachments i>before the MTA tries to deliver the message to a maildir... procmail is normally accessed via a .forward or .qmail file in the users home directory.

Are you planning to strip out exe files and other 'junk'? If so you should check out SpamAssasin.

update: Roger's answer looks even better.

Parsing out the username is easy, if you have the SMTP envelope, or the recipient email address. (If you don't, it's not possible in the general case, since the TO header frequently does not contain the recipient's email address.)

if ($toaddress =~ /(\S+)[@]yourdomain|yourotherdomain/) {
   $user = $1;
} else {
   warn "Unknown user:  $toaddress\n";
   $user = 'postmaster'; # Or whoever should get slop.
}
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If you don't have the envelope available, you can TRY to get the recipient's address from the To or Cc fields. Something like this might work most of the time:

# This is untested.
@users = map {
  /^(\S+)[@]/ ? $1 : undef
} grep {
  /(yourdomain|yourotherdomain|yourthirddomain)$/
}  map {
  s/\".*?\"//g;
  (/[<](\S+?)[>]/) ? $1 : undef
} map {
  split /,\s*/, $_
} $headers =~ m/^(?:To|Cc)[:]\s*(.*?)$/mig;
if (not @users) {
  warn "No users.\n";
  @users = ('postmaster');
}
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For the attachments, you probably want to look at MIME-related modules on CPAN, such as MIME::Tools.

Placing the thing in the user's home directory should be easy. Assuming *nix, you'd use something like this:

  my $filename = "attachment"; {
    my ($y, $m, $d) = (localtime)[5,4,3];
    $y += 1900; $m += 1;
    $filename = join "-", $filename, $y, $m, $d;
  }
  # I assume $user and $ext are already set to the
  # username and the filetype extension respectively.
  while (-e "/home/$user/$filename.$ext") {
    $filename .= ('a'..'z')[rand 26];
    # It is possible to be more elegant than this.
  }
  open FILEHANDLE, ">/home/$user/$filename.$ext";
  binmode FILEHANDLE; # Probably not necessary on *nix.
  print FILEHANDLE $content;
  close FILEHANDLE;
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You'll need write permissions in the user's directory. If that's a problem, you can change the /home/ prefix and instead use some neutral location where all the users have directories but you have write permissions to all of them (e.g., by belonging to the group that owns them). The root user could if desired then create a link to each user's attachments directory within his home directory.

$;=sub{$/};@;=map{my($a,$b)=($_,$;);$;=sub{$a.$b->()}}
split//,".rekcah lreP rehtona tsuJ";$\=$ ;->();print$/
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I need a script that will look at an arriving email. It will then strip the attachment (gif or jpeg only). It will then place the attachment into the users folder.

Ahh... yess.... This gives me flashbacks to when I worked for a major financial company just prior to Y2K. I was given the assignment to write a script similar to what you are describing. This was part of the paranoia that existed around Y2K in that management was concerned that viruses contained within binary attachments would infiltrate the network and wanted attachements "jailed" until January 5, 2000 after being virus inspected. I named the script "mailStripper" and collaborating with my bretheren in the messaging group we put the script on two machines named "chip" and "dale". I announced this in a meeting with senior VPs with an absolute straight face by my manager at the time absolutely lost it. (I didn't warn him!)

Anyway enough of the war story! This is certainly a case of TIMTOWTDI! I echo what Brother Roger says in suggesting that you look at Mail::Message::Attachment::Stripper but also look at the whole family of MIME:: modules on CPAN. Psuedocode for how my script worked looked like:

Open the message.
Does it have attachments?
Yes: Inspect each attachment
     is it one of the allowed types?
     Yes: leave attachment intact
      No: Strip the attachment 
          replace it with a note to the end user 
          that it has been stripped and jailed.
No: send message on without being molested.
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Unfortunately I didn't keep a copy of the script around so I can't post it here.

#!/usr/bin/perl
use Mail::MboxParser;

my $mb = Mail::MboxParser->new('Mboxtest', decode => 'ALL');

#or 
#my $mbox= \*STDIN; 
#my $mb = Mail::MboxParser->new($mbox); 

# slurping 
for my $msg ($mb->get_messages) {
print "###########################################################\n";
print $msg->header->{subject}, "\n";
print $msg->header->{from}, "\n";
print "###########################################################\n";
$msg->store_all_attachments('tmp');
my ($body) = $msg->body($msg->find_body,0);
print ($body->as_string);
print "###########################################################\n";
}
print "############################################################\n"
+;
print "############################################################\n"
+;
print "############################################################\n"
+;



# we forgot to do something with the messages 
$mb->rewind;
while (my $msg = $mb->next_message) {
# iterate again 
# ... 
}
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