Andreas Prieß wrote:
> Hi,
>
> in few words: should MUAs be allowed to set an empty sender (or what
> else is happening here)?
>
> I sometimes see an empty sender comming in from authenticated users
> MUA like this in my log:
>
> 2007-11-22 10:45:02 1Iv8cH-0000Xc-Ps <= <> H=p57b2e2c9.dip.t-dialin.net
> (Bro) [87.178.226.201] P=esmtpsa X=TLSv1:RC4-MD5:128
> A=auth_login:localuser@??? S=2663
>
> 2007-11-22 10:45:02 1Iv8cH-0000Xc-Ps => externaluser@???
> R=dns_lookup T=remote_smtp H=mailin.rzone.de [81.169.145.100]
>
> 2007-11-22 10:45:02 1Iv8cH-0000Xc-Ps Completed
>
>
> Because the users are authenticated, the messages are handled in
> submission mode, with the $authenticated_id being the qualified address
> of the user:
>
> accept authenticated = *
> control = submission/domain=
>
> The docs say, submission mode fixes From: and adds Sender: Headers.
>
> But what will the envelope sender look like to the external MTA? Will
> this be sent as if it was a bounce message? And does this have to be
> permitted for some reason or should this be blocked?
>
> What I know is, the users where I see this use Outlook or Outlook
> express and most of their messages show the correct sender address in
> the logs.
>
> Thanks for any hint.
They are most likely to be delivery and read notify messages generated
by the client and/or email server. They should maintain their null
sender to remove the chance of mail loops.
Generally a pretty benign item.
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