#!/usr/bin/perl
use MIME::Entity;
use Net::SMTP;

# create the multipart message with attachments 
$msg = MIME::Entity->build(
    Type => 'multipart/mixed',
    From => 'bogus@mail.com',

    # The "To" here is displayed in the message header as "To" 
    # This is not the actual list of recipients 
    To => '"Display Name" <user1@mail.com>, "Second Person" 
<user2@mail.com>',
    Subject => 'Automatic email of Excel report',
);
$msg->attach(
    Type     => 'application/msexcel',
    Path     => $report,
    Filename => 'college_orders.xls',
    Encoding => 'base64'
);
$msg->attach(
    Data => "Enclosed is the daily report of orders. 
(automated delivery)"
);

# send the message 
$smtp = Net::SMTP->new("smtp.mail.com");

#authenticate if required 
$smtp->auth( "login", "passwd" );

# Identify yourself to the smtp server 
$smtp->mail('bogus@mail.com');

# The syntax for "To" is different in MIME::Entity and Net::SMTP 
# The "to" here is the list of actual recipients and is not displayed 
$smtp->to( 'user1@mail.com', 'user2@mail.com' ) || die "Bad address";

# Send the message and attachments 
$smtp->data( [ $msg->as_string ] ) || die "mail not accepted";
$smtp->quit;

exit;
[download]

And since you are using sendmail in your question, here is how to do attachments with sendmail manually. You may have to adjust the content type for .xls (I never use it so I'm guessing). You can see, modules make it alot easier, setting up the multipart boundaries for you.