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Groups > alt.comp.software.thunderbird > #16474

Re: I Have Become an "Undisclose Recipient"

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croy <croy@spam.invalid.net> wrote:

> When I look thru emails that I have received over the last decade, I see
> the Recipient (me) is listed as "Undisclosed recipient".  I'm not sure when
> this started, but I'm pretty sure it was after Thunderbird version 102.

That is what the *sender* put in the To or Cc header.  You were on a
mailing list.  It is rude to expose the e-mail addresses of other
recipients of a bulk mailing unless each recipient has granted
permission by the sender to expose their e-mail address (not likely).
However, many e-mail servers will reject outbound e-mails that have
blank To or Cc headers.  Some e-mail clients also do not allow blank To
or Cc headers in outbound messages.  So, something has to put in those
headers, like "Undisclosed recipient".  If the message is from a mailing
list, often the name of the mailing list is put in the To header, like
"To: Harry Potter Fan Club - East coast division", and the From might be
"From: Hogwarts Council".  An insulting sender could say "To: Dumbass at
Work".  The sender's client can put ANYTHING it wants in the
client-generated headers, like in the To and CC headers.  Whether the
sending mail server accepts it is another matter.

The To and CC headers are NOT used to address your e-mails to recipient.
Those are there for info to the users.  The e-mail client will aggregate
all recipients in the To, Cc, and Bcc *fields* in a new outbound e-mail
into one list of RCPT-TO commands, one for each recipient.  Your e-mail
client establishes a mail session with the server, sends a RCPT-TO
command for each recipient to the server, and then sends a DATA command
with the body of your message.  If you send your message to 10
recipients, your client issues 10 RCPT-TO commands followed by 1 DATA
command.  The server then sends a separate copy of DATA to each RCPT-TO.

Since the To and Cc headers do NOT actually specify where to route your
e-mails, you can put anything you want in those fields.  Depends on the
e-mail client you use.  Some bulk mailers will use bogus strings in the
To or Cc headers while using a mailing list to build the RCPT-TO command
list.  In fact, the client can specify a recipient that is not in a
RCPT-TO command.  *Clients* fill the To and CC headers, not the server.
That's why spammers can lie to whom they sent their turds.  They may
even put a recipient in the To header since few users define inbound
e-mail rules that filter out e-mails they sent to themself.  The spammer
looks like you sent yourself an e-mail, and you don't have a rule
looking for you sending to you.

The To and CC headers don't even need to contain e-mail addresses.  They
could have "Enlarge your penis", "Make millions", or "Undisclosed".
Those headers (added by the client) are NOT used to specify which
recipients get the e-mail.  It's the list of RCPT-TO commands from the
client to the server that specifies who are the recipients.

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Thread

I Have Become an "Undisclose Recipient" croy <croy@spam.invalid.net> - 2025-04-27 11:00 -0700
  Re: I Have Become an "Undisclose Recipient" Andy Burns <usenet@andyburns.uk> - 2025-04-27 19:07 +0100
  Re: I Have Become an "Undisclose Recipient" "Carlos E.R." <robin_listas@es.invalid> - 2025-04-27 20:24 +0200
  Re: I Have Become an "Undisclose Recipient" "David E. Ross" <nobody@nowhere.invalid> - 2025-04-27 13:00 -0700
  Re: I Have Become an "Undisclose Recipient" Laughing Policeman <invalid@invalid.net> - 2025-04-27 20:36 +0000
  Re: I Have Become an "Undisclose Recipient" VanguardLH <V@nguard.LH> - 2025-04-27 22:12 -0500
  Re: I Have Become an "Undisclose Recipient" croy <croy@spam.invalid.net> - 2025-04-28 11:12 -0700
    Re: I Have Become an "Undisclose Recipient" Frank Miller <miller@posteo.ee> - 2025-04-28 20:54 +0200
      Re: I Have Become an "Undisclose Recipient" croy <croy@spam.invalid.net> - 2025-04-28 16:52 -0700
        Re: I Have Become an "Undisclose Recipient" Frank Miller <miller@posteo.ee> - 2025-04-29 03:45 +0200
          Re: I Have Become an "Undisclose Recipient" NFN Smith <worldoff9908@gmail.com> - 2025-04-30 12:04 -0700

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