Is there a way to prevent certain parts of an email from being forwarded?

Question

Email

Hello.
So, let's say there is a part of the email (for simplicity, let's say this is a separate mime part), which contains an authorization link.
Question. Is it possible to make this part ignored when forwarding?
i.e. the user who received the letter with it will read it, but when forwarded to friends/replying to the letter, it will be ignored.
Or maybe that when forwarding this link ceased to be valid?
As an option, I considered sending it with an inline html/txt attack. Alas, it doesn't even show up.
Thanks in advance.
For adequate advice as always in karma =)

Answer 1

So there is probably no direct solution ready. The mailer is obliged to receive and send mail, he cares little about the internal contents. By the way, the mailer used was not indicated.
You need to look in the direction of different analyzing software (anti-spam / anti-virus).

Answer 2

As far as I understand the work of mail protocols, this is technically impossible - even intermediate headers added by servers during transmission are copied.
When forwarding (forwarding) mail messages, the letter is also copied, the mailer can optionally change (quote, throw out attachments), but this is not a standard and you cannot be sure.
Further, the logical side is that the user, sending the letter, takes full responsibility for the content of the letter (suddenly there is his password), and therefore it is solely in his will to delete or leave any content.
And the last thing: usually mailers (for example, GMail for sure) automatically show an attachment of the text\html type, if there is one, and the html display mode is enabled, while not showing the text.
Sorry I couldn't help =)

Answer 3

Only one thing came to my mind, though a crutch:
In the letter, place a picture on an external server. On this picture display some activation code. The point is that the picture is shown only 1 time, i.e. at the second request, write to the user something like "repeat the authorization request." Although this method, of course, is also not a fanatic, because no one bothers to send the letter without opening it.

Answer 4

As an option, make such a link a one-time and limited-time action.
If the user has already poked it once, then it is no longer valid and can be sent.
And if you didn’t poke, then alas.

Answer 5

Can inline somehow not so form? And thunderbird and the bat! and webfaces show this inline:
From: [email protected]
To: [email protected]
Subject: Test
Mime-Version: 1.0
Content-Type: multipart/mixed;
boundary="--example"
----example
Content-Type: text/plain; charset=Windows-1251
Content-Transfer-Encoding: 8bit
Content-Transfer-Disposition: inline
This is a link:
----example
Content-Type: text/plain; charset=Windows-1251
Content-Transfer-Encoding: 8bit
Content-Transfer-Disposition: inline
www.example.com/
----example--
albeit in a different way, and the forwarding behavior is almost as desired.