[perl #60798] [BUG] [META] Lack of 'To:' header may impede deliverability of email

# New Ticket Created by  James Keenan 
# Please include the string:  [perl #60798]
# in the subject line of all future correspondence about this issue. 
# <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=60798 >


Here are the headers I get when I receive an email due to my  
subscription to [email protected]:

	From: 	  [email protected]
	Subject: 	[perl #38183] [TODO] smoke - possible 'Cross Site  
Scripting' issue
	Date: 	November 24, 2008 4:49:39 PM EST
	Cc: 	  [email protected]
	Reply-To: 	  [email protected]

Here are the headers I get when I receive an email due to my  
subscription to [email protected]:

	From: 	  [email protected]
	Subject: 	Re: [parrot-tickets] [Parrot] #6: [TODO] remove  
VtableCache PMC
	Date: 	November 24, 2008 5:21:54 PM EST
	Cc: 	  [email protected]
	Reply-To: 	  [email protected]

Note the absence of a 'To:' header in each email.  I believe this may  
cause Parrot email to be rejected as spam by anti-spam programs and  
Internet service providers.

I am employed by a major email service provider -- the type of  
business that lives or dies on the basis of whether the email it  
sends is actually delivered to the intended recipients.  I consulted  
with one of the deliverability experts at the company about the  
absence of 'To:' headers.  He confirmed my suspicion that the absence  
of a 'To:' header could lead to rejection of our email.

I became aware of this because I have long run a crude anti-spam  
program before downloading my email from my ISP.  Whenever I receive  
an email lacking a 'To:' header, I get a classic Perl 5 uninitialized  
value warning:

   Use of uninitialized value $headers{"To"} in concatenation (.) or  
string at ... line 153, <STDIN> line 1.

Until I started to (really, had to) subscribe to parrot-dev, I could  
be certain (99% confidence level) that any email I received without a  
'To:' header was spam.  So if my amateur program flags parrot-dev and  
parrot-tickets email as possible spam, what might professional  
programs do.

I'll concede that I have no evidence that our email is already being  
rejected, but I think that, at the very least, delivering our mail to  
'Cc:' rather than to 'To:' should be made public.

Thank you very much.
kid51