[Mailman-Users] From Address and non-member posts

[Brad Knowles]

At 5:16 PM +0100 2004-06-30, Ian A B Eiloart wrote:

>>>  > 1. When I post to my mailming list the From address comes like
>>>  > "mylist-bounces at mydomain.com". Why can't I have the from address as
>>>  > the address of the sender?
>>>
>>>  Because that's where bounces go, and you want automatic unsubscription
>>>  to work, don't you?
>>
>>  And, as a subscriber, I don't want all the bounce messages coming to me!
>>   As Ralf says, let mailman see the bounces and deal with them.
>
>  No, that's wrong. The question was about the "From:" address. Bounces
>  go to the "Sender:" address. The from address has to be the person who
>  composed the message. The sender address is the agent that sent it to
>  the recipient.

	There is the header "From:" field, and then there is the envelope 
sender address.  The latter is sometimes indicated as something like:

		From <iane at sussex.ac.uk>

	In particular, note the lack of a colon after the word "From". 
This is sometimes indicated as the "From_" address, where the 
underscore character is understood to stand for a space character in 
this usage.

	It is not exactly clear to me which one is being referred to 
here.  The original quote does not indicate a colon after the word 
"From:", but I'm not 100% certain as to whether or not the author was 
aware of this connotation.


	Note that some MTAs will promote the envelope sender address into 
the header "From:" field (especially if no header "From:" field 
exists), and some MUAs display an address listed in the "Sender:" 
field in addition or in place of the "From:" field (if they are 
different).

	Bounces are sent to the envelope sender address, which may or may 
not be recorded in the "Sender:" field, or elsewhere in the message. 
It's important to distinguish between the envelope sender address and 
the contents of the "From:" and "Sender:" fields, because the 
envelope sender address may be lost or irretrievably altered once the 
message is received.


	You should never attempt to bounce a message to any address in 
any header field -- you should always bounce back to the actual 
envelope sender address.  This obviously causes problems if the 
envelope sender address is lost or irretrievably altered.

-- 
Brad Knowles, <brad.knowles at skynet.be>

"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety."
     -Benjamin Franklin, Historical Review of Pennsylvania.

   SAGE member since 1995.  See <http://www.sage.org/> for more info.