On Jun 11, 2004, at 09:55, Dennis Davis wrote:
> Problems may arise if exim is being used as a relay. You won't
> necessarily know what systems you are delivering mail to, or
> receiving mail from. There may be a good risk of confusion if
> different systems are using the same operator (+) for totally
> different purposes.
Hmmm. Let us say that <joe@???> sends a message to
<jane@???>. Joe's MTA modifies the envelope-from to
<joe+abcdef.crypt@???>, then delivers the message through a
smarthost at "smtp.joe-isp.com".
Let us suppose that "joe-isp.com" modifies the envelope-from further,
to something like:
<joe+abcdef.crypt+joehost.com@???>
Jane has a vacation file, and so "janehost.com" returns a DSN back to
this newly constructed address. "joe-isp.com" would _HOPEFULLY_ strip
off the portion after the last "+" sign, then relay the message back to
<joe+abcdef.crypt@???>.
IMO this seems a bit theoretical. Normally, the outbound mail
exchanger of a domain would be the only machine that has authority to
modify the envelope-from.
If the message were to be resent by a mailing list, that would be
another matter. For instance, the envelope-from in all mails sent from
the "Debian-private" mailing list is of the form:
<bounce-debian-private=subscriber=subscriber.domain@???>
Here, they have full control of the envelope-from, and that of the
original message is irrelevant.
Maybe I am missing something in what you were saying..
-tor
