Instead of inventing Yet Another Templating Solution, you might also consider Template Toolkit. Here's something I whipped up in 5 minutes from your source. Note the alternative provided for sender email:

#!/usr/bin/perl -w 
use strict; 
$|++; 
 
use Template; 
 
my $result = Template->new 
  ( 
   START_TAG => '<', END_TAG => '>', 
  )->process(\*DATA, 
             { 
              recp_name => 'Recipient name', 
              send_name => 'Sender name', 
              ## send_email => 'sender@example.com', 
              site_url => 'http://example.com/some/place', 
             }) || die Template->error; 
 
__END__ 
Hey <recp_name>, 
 
I was surfing the web and I stopped by a pretty cool site that I think
+ you 
might be interested in.  It is filled with cool information, good link
+s, funny 
pics, and more, so be sure to check it out! 
 
Here is the address of the site: <site_url>. 
 
<send_name> 
<IF send_email; send_email; ELSE; "[no email specified]"; END>
[download]

-- Randal L. Schwartz, Perl hacker