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Re: [ietf-dkim] Mailing lists as 2822-Sender (was: Responsibility vs. Validity)

2007-12-05 14:34:50
Dave Crocker wrote:

Tony Finch wrote:
     "The "Sender:" field specifies the
   mailbox of the agent responsible for the actual transmission of the

Popular MTA implementations (Sendmail, Postfix) do not implement the
Sender: header the way 822 and 2822 suggest,

How would you describe what they do do?

Well, if SendMail/PostFix is operating like the rest of the world... If missing, a SMTP receiver MIGHT do:

   Sender: <-- x821.MailFrom

in the same vain many SMTP receivers will fill in the missing 822 required fields.

   FROM:  <<-- x821.MailFrom
   To:    <<-- x821.RcptTo

and they MUST do this if they want to SUPPORT the presentation layers.

But sender is not a given because it is not a 822 required field. In fact, I seem to recall, it was only in recent years that we even bothered with Sender in our mailers.

Only a few sites will reject such empty headers in the DATA block. Off hand, I know of one, HOTMAIL.COM and they only started to reject mail without the headers when SENDER-ID support was added to HOTMAIL.COM.


Hector Santos, CTO

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