At 1:02 PM -0400 6/19/05, Stefan Jeglinski imposed structure on a
stream of electrons, yielding:
Not sure the question is phrased correctly, but I have wondered
about this for a while.
When an MTA makes a connection, it sends an e-mail via an envelope
address, no?
Yes.
There is no necessary correlation between this envelope address and
the recipient's To address.
Right.
IOW, [EMAIL PROTECTED] can end up with an e-mail in his inbox that
appears to have been sent "To" [EMAIL PROTECTED], even if sam doesn't
exist. This is an endless source of confusion to recipients that
don't know how things work. And obviously I don't quite know how it
works either.
Do all MTAs necessarily transmit the envelope address for display?
No.
The only way SIMS can deliver is when it gets a legit envelope
address, no? In Eudora, there is a header called x-envelope I can
turn on, but no envelope header appears in received e-mail that I
can tell.
That's not actually Eudora creating that header, but rather Eudora
hiding it if you have it set to hide it. Some MTA's will add that
header.
What really determines how an end-user can see the envelope address,
if ever at all?
With SIMS, the envelope recipient will appear in the SIMS-added
Received header IF the message hads only one envelope recipient.
That hints at why there is no standard way to record the envelope
recipient: there can be more than one. Back before spammers made it
useful to shun such mail and before AOL established mystery bounces
as a de facto standard, a lot of mail for mailing lists was delivered
as one copy per domain with multiple envelope recipients (i.e. RCPT
commands in SMTP) to save on bandwidth and delivery time. This is
still sometimes used today but is less common than it used to be
because of the degraded trust and reliability of the mail system
brought on by both conscious abusers (spammers) and by shoddy mail
system design and implementation (e.g. AOL, until the past couple of
years.) SIMS puts a 'for' clause into its Received header when there
is a single envelope recipient, but in the rare cases where there are
multiple recipients it does not do so as a privacy protection.
--
Bill Cole
[EMAIL PROTECTED]
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