The 2 easiest modules to use are Net::POP3 and Mail::POP3Client About the only glitch you may run into is the type of auth the mail server uses, the port, and if ssl is used. But the module should take care of this automatically. Another glitch is if you have the email address as your logon name, you must either \ the @ or single quote the name.

Here is a simple filter I use.

#!/usr/bin/perl -w
use strict;
use Net::POP3;

my $maxsize = 50000;
my (@fromgoodre,@frombadre,@badwordre,@maillistre,@badcontentre,@recei
+vedgoodre,@togoodre);

my %rehash = (
   'fromgood' => \@fromgoodre,
   'frombad' => \@frombadre,
   'badwords' => \@badwordre,
   'maillist' => \@maillistre,
   'contentbad' => \@badcontentre,
   'receivedgood' => \@receivedgoodre,
   'togood' => \@togoodre
);

foreach my $file (keys %rehash){
  open(FH,"< $file") or warn "Can't open $file $!\n";
  chomp (my @lines = <FH>);
     foreach my $line(@lines){push(@{$rehash{$file}},qr/$line/i) if $l
+ine =~ /\w/}
                                     #removes tabs, empty lines from b
+ecoming regexes
close FH;
}

my $ServerName = "mail.foobar.com";
my $pop3 = Net::POP3->new($ServerName)||die("Couldn't log on to server
+\n");
my $UserName = 'fuzzball@foobar.com';
my $Password = "goofy";

my $num_messages = $pop3->login($UserName, $Password)||die("Bad userna
+me or password\n");
my $messages = $pop3->list();
print "******$messages Number of messages->$num_messages*******\n";
my %messages;
my ($flag,$msg_id,$messcheck,@del_mess,@header,@top,$line);
@del_mess = (); 
$messcheck = '';
print "####################################################\n"; 

foreach $msg_id(keys %{$messages}) {
     $flag = '';
     my @header =(); #array for headerlines
     my @top = ();  #array for top of messagebody
     my $messref = $pop3->top($msg_id,10);
     my $size = $pop3->list($msg_id);
     print "message$msg_id->size=$size\n";
#     print "@$messref";
     print "----------------------------------\n";

     while(1){  
       my $line = shift @$messref;
       last if $line =~ /^\s*$/; 
       push(@header,$line);
     }
     @top = @$messref; 
     print '~~~~~~~~~~~~~~~~~~@header ->',"\n@header\n";
     print '~~~~~~~~~~~~~~~~~~@top ->',"\n@top\n";


#check X-Mailinglist:
          if(($line) = grep(/^X-Mailinglist:/o,@header)){
             print "#################X-Mailinglistline-> $line\n";
             for my $maillistre (@maillistre) {
                      if ($line =~ /$maillistre/) { print "Mail list g
+ood\n"; $flag = 'ok'; goto DOBODY}
                   }
      }
#check From
           ($line) = grep(/^From:/io,@header);
       print "#################Fromgrepline-> $line\n";
       my $from = $line;        
            for my $goodfromre (@fromgoodre) {
                      if ($line =~ /$goodfromre/) { print "GoodFrom->$
+goodfromre\n"; $flag = 'ok'; goto DOBODY}
                  }
                  for my $badfromre (@frombadre) {
                      if ($line =~ /$badfromre/) { print "BadFrom->$ba
+dfromre\n"; push(@del_mess,$msg_id); $messcheck .= "$msg_id -> $badfr
+omre ->$from\n"; $flag = 'bad'; goto DOBODY}
                  }
            
#check To and CC and Return-Path
        ($line) = grep(/^(To|Cc|Return-Path):/io,@header);
        print "#################To-CC-ReturnPathgrepline-> $line\n";
             for my $togoodre (@togoodre) {
                      if ($line =~ /$togoodre/) { print "ToCCReturn-Pa
+th address good ->$togoodre\n"; $flag = 'ok'; goto DOBODY}
                   }
                 for my $badfromre (@frombadre) {
                      if ($line =~ /$badfromre/) { print "BadReceived-
+>$badfromre\n"; push(@del_mess,$msg_id); $messcheck .= "$msg_id -> $b
+adfromre ->$from\n"; $flag = 'bad'; goto DOBODY}
               }

#check Received        
       if(($line) = grep(/^Received:/io,@header)){
             print "#################Receivedgrepline-> $line\n";
             for my $receivedgoodre (@receivedgoodre) {
                      if ($line =~ /$receivedgoodre/) { print "Receive
+d address good\n"; $flag = 'ok'; goto DOBODY}
                   }
             for my $badfromre (@frombadre) {
                      if ($line =~ /$badfromre/) { print "BadReceived-
+>$badfromre\n"; push(@del_mess,$msg_id); $messcheck .= "$msg_id -> $b
+adfromre ->$from\n"; $flag = 'bad'; goto DOBODY}
                   }
        }
        
#check Content-type
            if(($line) = grep(/^Content-Type:/o,@header)){
        print "#################Content-typegrepline-> $line\n";
             for my $badcontentre (@badcontentre) {
                      if ($line =~ /$badcontentre/) { print "Bad Conte
+nt->$badcontentre\n"; push(@del_mess,$msg_id); $messcheck .= "$msg_id
+ -> $badcontentre ->$from\n"; $flag = 'bad'; goto DOBODY}
                   }
            }
        
#check Subject        
            ($line) = grep(/^Subject:/io,@header);
        print "#################Subjectgrepline-> $line\n";
                 for my $badwordre (@badwordre) {
                      if ($line =~ /$badwordre/) { print "badword in s
+ubject->$badwordre\n"; push(@del_mess,$msg_id); $messcheck .= "$msg_i
+d -> $badwordre ->$from\n"; $flag = 'bad'; goto DOBODY}
                  }

#check for base64                    
    if(($line) = grep(/^Content-Transfer-Encoding: base64/o,@header)){
        print "#################base64grepline-> $line\n";
            if ($line =~ /^Content-Transfer-Encoding: base64/o){print 
+"base64 content\n"; push(@del_mess,$msg_id); $messcheck .= "$msg_id -
+> base64 ->$from\n"; $flag = 'bad';goto DOBODY}
         }
     
#check Message-Id
            ($line) = grep(/^Message-ID:/io,@header);
        print "#################Message-Idgrepline-> $line\n";
            if (($line !~ /.*<?.+@.+(\..+)?>?$/o) || ($line =~ /\@127\
+.0\.0\.1/o))
             { print "Bad Message-Id\n"; push(@del_mess,$msg_id); $mes
+scheck .= "$msg_id -> bad Message-Id ->$from\n"; $flag = 'bad'; goto 
+DOBODY}

DOBODY:
if ($flag eq 'ok'){print "Message $msg_id is OK\n"; line(); next}
if ($flag eq 'bad'){print "Message $msg_id is bad\n"; delmessage($msg_
+id); line(); next}
if ($size > $maxsize){print "Size limit exceeded\n"; push(@del_mess,$m
+sg_id); $messcheck .= "$msg_id -> size limit exceeded ->$from\n"; $fl
+ag = 'bad'; goto DOBODY}
#do body check
print "Doing body check\n";
    for my $line (@top){
         for my $badwordre (@badwordre) {
         if ($line =~ /$badwordre/) { print "badword in body->$badword
+re\n"; push(@del_mess,$msg_id); $messcheck .= "$msg_id -> bad word in
+ body ->$badwordre ->$from\n"; delmessage($msg_id); line(); goto FINI
+SH}
       }
    }
FINISH:
line();
print "\n";
}

#confirm the deletions
line();line();line();line();
unless(defined $del_mess[0]){print "No messages to be deleted\nHit Ent
+er to quit\n"; my $input = <>; $pop3->quit(); exit}
print "Bad Messages:\n$messcheck\n\n";
print "Delete above messages?\n  [yY] then Enter to delete, or Enter t
+o abort\n";
chomp(my $input = <>);
if($input =~ /^[yY]$/i){foreach(@del_mess){print "Deleting message $_\
+n"; $pop3->delete($_)}}

$pop3->quit();

sub delmessage{print "Message @_ to be deleted\n"}
sub line {print "####################################################\
+n"}
exit 0;
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