Using mainly Send mail with attachment using only SMTP with some hints from Sending attachments in emails using SMTP here is what I have: 
my $msg      = "foo";
my $subj     = get_datetime();
my $csvfile  = "opnet_ace_cap_agent_audit_$subj.csv";
my $boundary = 'frontier';


my $smtp = Net::SMTP->new('smtp.somecorp.com', Timeout => 60);
$smtp->mail( "root\@$hostname.somecorp.com" );
$smtp->to( @to);
$smtp->data();

foreach my $dst ( @to ) { $smtp->datasend( "To: $dst\n" ) }
# @to is a global (ducks for cover)

$smtp->datasend("Subject: Opnet: Ace Capture Agent Audit: $subj\n");
$smtp->datasend("\n");

$smtp->datasend("Content-type: multipart/mixed; \n\tboundary=\"$bounda
+ry\"\n");
$smtp->datasend("MIME-Version: 1.0\n");

$smtp->datasend("\n--$boundary\n");

$smtp->datasend("Content-type: text/plain\n");
$smtp->datasend("Content-Disposition: quoted-printable\n");
$smtp->datasend("\n$msg\n");

$smtp->datasend("--$boundary\n");

$smtp->datasend("Content-Type: application/text; name=\"$csvfile\"\n")
+;
$smtp->datasend("Content-Disposition: attachment; filename=\"$csvfile\
+"\n");
$smtp->datasend("\n");
$smtp->datasend(\@csv);  # Global array (ducks for cover again).

$smtp->datasend("--$boundary--\n");

$smtp->dataend();
$smtp->quit;

[download]
And this is what I am getting: 
X-Message-Delivery: Vj0xLjE7dXM9MDtsPTE7YT0xO0Q9MTtTQ0w9MA==
X-Message-Status: n:0
X-SID-PRA: root@nexus6.somecorp.com
X-Message-Info: JGTYoYF78jHHuiSNiwoFu0whHwJgX/CsT9mqf3HC10h8SNpkHwOrgZ
+mf4Gx8BxnSmZ+h/1ABqtNbvbB/F7nK1sjKX60rxMi2
Received: from smtp2.somecorp.com ([x.x.x.x]) by col0-mc4-f8.Col0.hotm
+ail.com with Microsoft SMTPSVC(6.0.3790.3959);
     Fri, 26 Jun 2009 19:35:38 -0700
Received: from foo.somecorp.com ([x.x.x.x]) by smtp2.somecorp.com with
+ Microsoft SMTPSVC(6.0.3790.3959);
     Fri, 26 Jun 2009 21:35:38 -0500
X-TM-IMSS-Message-ID:<1ecc05ff0013bcbe@foo.somecorp.com>
Received: from localhost.localdomain (x.x.x.x) by
 bar.somecorp.com (x.x.x.x) with Microsoft SMTP Server id
 x.x.x.x; Fri, 26 Jun 2009 21:35:36 -0500
To: <me@somecorp.com>, <me@msn.com>
Subject: Opnet: Ace Capture Agent Audit: 2009_06_26_21-35-37
MIME-Version: 1.0
Content-Type: text/plain
Message-ID: <de015822-96f4-435a-a299-95f70950d70a@bar.somecorp.com>
From: <root@somecorp.com>
Return-Path: root@comecorp.com
Date: Fri, 26 Jun 2009 21:35:36 -0500
X-OriginalArrivalTime: 27 Jun 2009 02:35:38.0504 (UTC) FILETIME=[F4F3A
+080:01C9F6CF]

Content-type: multipart/mixed; 
    boundary="frontier"
MIME-Version: 1.0

--frontier
Content-type: text/plain
Content-Disposition: quoted-printable


Fail
----
SOMEHOST
SOMEHOST
SOMEHOST

Host Unreachable
----------------
thevoid

Pass
----
SOMEHOST
SOMEHOST
SOMEHOST
SOMEHOST
SOMEHOST
SOMEHOST

--frontier
Content-Type: application/text; name="opnet_ace_cap_agent_audit_2009_0
+6_26_21-35-37.csv"
Content-Disposition: attachment; filename="opnet_ace_cap_agent_audit_2
+009_06_26_21-35-37.csv"

rc,host,resolved_name,elapsed_time
1,SOMEHOST,x.x.x.x,0.0012669563293457
1,SOMEHOST,x.x.x.x,0.00101494789123535
1,SOMEHOST,x.x.x.x,0.00100302696228027
1,SOMEHOST,x.x.x.x,0.000874996185302734
0,SOMEHOST,x.x.x.x,5.00376486778259
0,SOMEHOST,x.x.x.x,5.00477504730225
1,SOMEHOST,x.x.x.x,0.00123500823974609
1,SOMEHOST,x.x.x.x,0.000978946685791016
0,SOMEHOST,x.x.x.x,0.00164794921875
undef,thevoid,undef,undef
--frontier--

[download]

So the multipart stuff isn't making it through. Any ideas?

Using ActivePerl 5.10.0 on Solaris SPARC. And I need to use core modules. (>.<)

Update1: Just to be clear, the output is from a "View Message Source" via Microsoft Hotmail. So I am receiving the message, but the multipart is completely broken -- everything after the "X-OriginalArrivalTime" line is the body of the message!

Also, in the actual code I have an "|| die" for every $smtp-> line so I know they are not failing outright (Update3: sorry I forget to mention this). And the output from get_datetime looks like: "2009_06_26_21-35-37" (which can be seen in the output I pasted in).

In case it matters, the mail server I am sending this through is Exchange (I think Exchange 2007).

I'm not an expert on SMTP, MIME, etc. so my guess is I'm doing something wrong in that regard.

Update2: Solution: ig nails it in Re^3: Problems sending an email attachment using Net::SMTP. Thanks so much for the help!!!

In reply to Problems sending an email attachment using Net::SMTP by Argel

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