[exim] Re: Handle sender on forwarding

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Author: Sebastian Nielsen
Date:  
To: 'Mailing List'
Subject: [exim] Re: Handle sender on forwarding
>>Why do you remove ARC signatures ?

Because they have no relevance when you have rewritten both MAIL FROM, RCPT
TO, and MIME From, and MIME To.
If the mail is forwarded again, then both second forwarding server and final
server will test against YOUR server, so it's the second forwarding server
that in that case should add ARC signatures.

But forwarding in 2 step is uncommon and useless, better to aim both
forwarding addresses to the same final address.

>>That might help the message reach the mailbox, but the recipient will
>>have to look harder to see who the message claims to have been
>>originally sent by.


Agreed with that. The info is in "Reply-To" instead.
It's a tricky thing, because writing

From: "original_sender@???" <forwarded_user@???>

may trip anti-phishing / anti-spam systems.

If you absolutely must preserve sender information, encapsulate the mail in
a new message/rfc822 object instead...

So a mail that looks like this (if forwarded_user is a forward to
example@???):

From: original_sender@???
To: forwarded_user@???
Subject: Hey
Content-Type: text/plain

Is sent as:

From: forwarded_user@???
To: example@???
Subject: Fwd: Hey
Content-Type: message/rfc822; boundary=1234

    Encapsulated email follows
    --1234
    From: original_sender@???
    To: forwarded_user@???
    Subject: Hey
    Content-Type: text/plain
    --1234--



>>Note. This example is confusing


Oooh sorry about that.
I tried to be clear with youruser@??? being the sender,
forwarded_user@??? being the address with a forward configured, and
somewhere@??? being the forward target.

Replaced youruser@??? as original_sender@??? instead.


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