Mail::DKIM how to sign emails before sending?

I just have to call it from a PHP page, so can be either.

the only emails that will be sent from the server is for new members and newsletters. the server won't receive email. am I on the right path?

Well, you said you just wanted to not have the e-mails end up in a users spam folder.  Whether a message is flagged as spam or not is up to the client.  I'm not familiar with the dkim project, and don't know if any mail clients are either, so this may or may not help solve that problem.

Either way, there is an example of how to send a signed message on the Mail::DKIM::Signer documentation page:
http://search.cpan.org/~jaslong/Mail-DKIM-0.28/lib/Mail/DKIM/Signer.pm

thanks for the detailed responses. and you're right DKIM is a HUGE pain to setup.

1) I had already setup Sender-ID. all I did was add the following SPF record to say that my IP for my server can send email. that's all I needed, right?
@
TXT
v=spf1 a ?all


2) I'm NOT on a shared IP. I've recently moved to a new server with a new IP and still many users with Hotmail, Yahoo and AOL complain they're not receiving it or it's in their spam folder. so don't think it's the IP. although how can I confirm?

do you still think DKIM won't solve the problem? I read Yahoo supports it, which is why I originally starting trying to set it up.

thanks MasonWolf for the continued help

1) I checked the blacklists, they all shows as "OK"

2) I sent an email to my gmail account and in the header it shows "Received-SPF: pass (google.com: domain of my_email designates my_server_ip as permitted sender)". so then I think that confirms Sender-ID works

3) my only idea left is to try and get DKIM working. After tons of problems I finally got it installed and setup in DNS without errors. now I think I just need to somehow sign the emails. I don't see how to use Mail::DKIM to do it with perl. and I couldn't find any PHP solutions. any ideas?

I have been putting off this problem for sometime. I would like to once and for all get this solved. I'm sure most webmasters have frustrations with this

I was able to send an email with perl

#!/usr/bin/perl

open(MAIL, "|/usr/sbin/sendmail -t");
print MAIL "To: $to\nFrom: $from\nSubject: $subject\n$msg\n";
close(MAIL);

but I don't see where to implement the DKIM signer.

but how do I send the $signature in the email:

open(MAIL, "|/usr/sbin/sendmail -t");
print MAIL "To: $to\nFrom: $from\nSubject: $subject\n$msg\n$signature\n"; #just add it to the end like this?
close(MAIL);

my $signature = $dkim->signature, returns a Mail::DKIM::Signature object.
To get a signature string:
my $sig_string = $signature->as_string();

The signature should be prepended to the message to make the resulting message. At the very least, it should precede any headers that were signed.

open(MAIL, "|/usr/sbin/sendmail -t");
print MAIL "$sig_string\nTo: $to\nFrom: $from\nSubject: $subject\n$msg\n";
close(MAIL);

thanks Adam314. I was able to send an email with the signature, but it didn't verify right. I sent an email to an address which verifies DKIM. it sent back:

DKIM Test: permerror (verification error: key DNS reply corrupt)

do you see anything I'm missing? we're so close

--------------------------------------------
Original message:
Date: Mon, 17 Sep 2007 15:36:09 -0700
Message-Id: <200709172236.l8HMa94E018519@mydomain.com>
DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=mydomain.com; h=to; q=dns/txt; s=dkim; bh=uoq1oCgLlTqpdDX/iUbLy7J1Wic=; b=c8v60Z56qFH2yeHCc6tdUtbMQS6qFqyJfvixNlut999mQsjLgIj5GuYAw0+/MZ8N9Ks9KfjGN8ATQnjWOG/jH12bc67vhpWLX1v7VE2wyy49EjDskJQls5ylZT580UbIq9yDGW1BGXMkpzrCbESwUGXkwr3WW+xrAs29azFtgOs=
To: autorespond+dkim@dk.elandsys.com
From: support@mydomain.com
Subject: Testing ...

This is a test message

Are all of these parameters correct:
my $dkim = Mail::DKIM::Signer->new(
                  Algorithm => "rsa-sha1",
                  Method => "relaxed",
                  Domain => "example.org",
                  Selector => "selector1",
                  KeyFile => "private.key");
             );

Also, is the info that is PRINTed exactly the same as the info in the message?
$dkim->PRINT("To: $to\n");
$dkim->PRINT("From: $from\n");
$dkim->PRINT("Subject: $subject\n");
$dkim->PRINT("$msg\n");

yes, tripled checked. all parameters are correct. I didn't get any errors sending the email. but the DKIM verifier couldn't validate the email

so I'm guessing either there's something else that needs to go in the header or something else I need to install. the error said "key DNS reply corrupt". so maybe the problem is after it receives the email and sending a command back to us to verify isn't working. what do you think?

I haven't ever used DKIM, so I'm going only from the documentation.  

Is your public key properly setup in DNS?
If it was recently changed, it is possible your old DNS entry is still being used, and will be for a short time (because of DNS cacheing).  

Here's my perl script. I tried a different dkim email verifier it came back with: "ERROR: Signed headers don't contain From header". not sure why such a different error than the other verifier. as for the DNS I added the single key to my domain as a TXT record when I installed DKIM like it said. Doesn't it also have to send a command back to the server to verify? If so, am I missing something?

---------------------------
#!/usr/bin/perl
use Mail::DKIM::Signer;
use warnings;
use strict;

##Email vars
my $to="dkim-test\@testing.dkim.org";
my $from= "support\@mydomain.org";
my $subject="Testing dkim";
my $msg="This is a test message";

##DKIM Processing
my $dkim = Mail::DKIM::Signer->new(Algorithm=>"rsa-sha1", Method=>"relaxed", Domain=>"mydomain.org", Selector=>"dkim", KeyFile=>"/usr/local/src/dkim-milter-2.2.1/dkim.private");
$dkim->PRINT("To: $to\nFrom: $from\nSubject: $subject\n$msg\n");
$dkim->CLOSE;
my $signature = $dkim->signature;
my $sig = $signature->as_string();


##Send Mail
open(MAIL, "|/usr/sbin/sendmail -t");
print MAIL "$sig\nTo: $to\nFrom: $from\nSubject: $subject\n$msg\n";
close(MAIL);

print "done";