[Mailman-Developers] Adding headers to mailman generated mails

[Brad Knowles]

At 4:46 PM -0800 2004/01/21, Somuchfun wrote:

>  Is there a problem to send out the emails one by one with individual To:
>  addresses and then add a header or a mail merge field in the footer without
>  creating bounce addresses that most MTA do not allow or understand?

	No MTA ever created should ever have a problem with VERPs.  Users 
might be confused by how they look, but the mail server should be 
able to deal with them just fine.  That's the entire point of VERPs.

	That said, if you don't want to do VERPs but you do want a single 
recipient per message generated by Mailman, you should just need to 
adjust the maximum number of recipients per message as specified by 
SMTP_MAX_RCPTS, and enable message personalization (see 
<http://www.python.org/cgi-bin/faqw-mm.py?req=show&file=faq02.002.htp> 
and 
<http://www.python.org/cgi-bin/faqw-mm.py?query=RCPT&querytype=simple&casefold=yes&req=search>). 
Just make sure that you don't enable actual VERP'ing along with these 
other changes.

	As part of the message personalization, add the appropriate 
per-user information in the template footer for the list.  That 
should hopefully deal with the problem.

>  I do not mind the additional CPU time for sending out the messages one by
>  one if it solves the problem for right now. But since the VERP bounce back
>  addresses do not really exist an Exim with verify = recipient will always
>  have a problem.

	This is almost certainly never a CPU time issue.  It's a disk I/O 
capacity issue.  See 
<http://mail.python.org/pipermail/mailman-developers/2001-June/008928.html> 
and the related "performance" entries in the FAQ.

	Not only can you kill your disk drive(s) on the server by 
specifying too few recipients per message, you can seriously reduce 
your message throughput and totally backlog the machine.  If you have 
a large enough list, you can easily make the machine bury itself to 
the point where it can not ever possibly recover from what was done 
to it.

>  So is there a way to tweak Exim into sending the messages individually and
>  allow the addition of a personalized footer without creating personalized
>  bounce-back addresses?

	I am not familiar with Exim.  I do not know what configuration 
changes would be required to get it to add personalized information 
in the headers.  You would need to talk to someone better acquainted 
with Exim, presumably on an Exim-specific mailing list or newsgroup.

	I don't remember whether or not postfix has a facility that would 
allow you to have it perform per-message/recipient header 
modifications.  I'd have to check the latest documentation, logs, 
etc....

	I can tell you that the default standard installation of sendmail 
will do this for you, automatically.  If there is one and only one 
recipient of a message, the "$u" macro will be defined, and the 
identified username will be shown in the "Received:" headers.  If 
there is more than one recipient for the message, then this macro 
will not be defined, and no usernames will be displayed.


	Unfortunately, most headers tend to be missing from most 
complaints, so your best bet would probably be to get Mailman to put 
the message personalization information into the footer of the 
message, which is more likely to survive.

-- 
Brad Knowles, <brad.knowles at skynet.be>

"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety."
     -Benjamin Franklin, Historical Review of Pennsylvania.

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