On 2/22/2007 14:47, Ronnie Streff wrote:
> This would also help facilitate rule making for routing postings to
> folders, and spam blockers (like that nasty earthlink beast) that block
> unknown e-mail addresses.
> 

Generally, server-side filters filter on the envelope-sender address, not the
'From:' address. The 'From:' address is not available for server-side processing
until the mail server accepts the entire message, because the 'From:' address is
part of the DATA portion of the SMTP transaction.

On the original message from the message author to the list address, the
envelope-sender address and the 'From:' address will almost always be the same.
When the message is distributed by the LISTSERV server, the envelope-sender
address will be in the form owner-$listname@$listhost; the 'From:' address will
not be changed.

Most modern email clients can be configured to filter on the 'Return-Path'
header, which contains the envelope-sender address.

-- 
Paul Russell, Senior Systems Administrator
OIT Messaging Services Team
University of Notre Dame
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