[PATCH] doc: process: add privacy warning when using some SMTP servers

[PATCH] doc: process: add privacy warning when using some SMTP servers

[sndanailov]

From: Sotir Danailov <sndanailov@wired4ever.net>

Warn the user about "Received" headers and how some
SMTP servers use them by attaching the user's IP addresses,
when using some email clients. Add suggestion on how to
test this behavior and how to avoid it.

Signed-off-by: Sotir Danailov <sndanailov@wired4ever.net>
---
 Documentation/process/email-clients.rst | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/Documentation/process/email-clients.rst b/Documentation/process/email-clients.rst
index fc2c46f3f82d..9c49f9b33fdb 100644
--- a/Documentation/process/email-clients.rst
+++ b/Documentation/process/email-clients.rst
@@ -350,3 +350,24 @@ although tab2space problem can be solved with external editor.
 
 Another problem is that Gmail will base64-encode any message that has a
 non-ASCII character. That includes things like European names.
+
+Privacy/Security
+----------------
+
+Keep in mind, that even if you're using a working email client, the SMTP
+server might have configurations you don't like.
+
+For example, if you decide to use the Gmail SMTP server with the Thunderbird
+client, the server will add your private and public IPs into "Received"
+headers, which are attached to all of your sent emails. This is done
+to avoid spam and to check where in the routing path an error might have
+occurred. Gmail's web GUI client doesn't add your IPs, because it's sent from
+Google's servers directly, not an external machine. Unfortunately the web
+client is not good for sending patches. You can check if your IPs are present
+in the headers by reading the raw email source.
+
+If you do not wish this behavior, you need to find a provider which doesn't
+do it or configure and host a SMTP server yourself.
+
+If you're concerned, always first send an email to yourself, read the email
+source and if you see no issues, continue to the mailing lists!
-- 
2.37.3

Re: [PATCH] doc: process: add privacy warning when using some SMTP servers

[Jonathan Corbet]

sndanailov@wired4ever.net writes:

> From: Sotir Danailov <sndanailov@wired4ever.net>
>
> Warn the user about "Received" headers and how some
> SMTP servers use them by attaching the user's IP addresses,
> when using some email clients. Add suggestion on how to
> test this behavior and how to avoid it.
>
> Signed-off-by: Sotir Danailov <sndanailov@wired4ever.net>
> ---
>  Documentation/process/email-clients.rst | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
>
> diff --git a/Documentation/process/email-clients.rst b/Documentation/process/email-clients.rst
> index fc2c46f3f82d..9c49f9b33fdb 100644
> --- a/Documentation/process/email-clients.rst
> +++ b/Documentation/process/email-clients.rst
> @@ -350,3 +350,24 @@ although tab2space problem can be solved with external editor.
>  
>  Another problem is that Gmail will base64-encode any message that has a
>  non-ASCII character. That includes things like European names.
> +
> +Privacy/Security
> +----------------
> +
> +Keep in mind, that even if you're using a working email client, the SMTP
> +server might have configurations you don't like.
> +
> +For example, if you decide to use the Gmail SMTP server with the Thunderbird
> +client, the server will add your private and public IPs into "Received"
> +headers, which are attached to all of your sent emails. This is done
> +to avoid spam and to check where in the routing path an error might have
> +occurred. Gmail's web GUI client doesn't add your IPs, because it's sent from
> +Google's servers directly, not an external machine. Unfortunately the web
> +client is not good for sending patches. You can check if your IPs are present
> +in the headers by reading the raw email source.
> +
> +If you do not wish this behavior, you need to find a provider which doesn't
> +do it or configure and host a SMTP server yourself.
> +
> +If you're concerned, always first send an email to yourself, read the email
> +source and if you see no issues, continue to the mailing lists!

So this seems to be just a description of how email works - the Received
headers always show the path through the net.  Is this really something
that we need to cover in the kernel docs?

Thanks,

jon

Re: [PATCH] doc: process: add privacy warning when using some SMTP servers

[Sotir Danailov]

On Thu 13 10 2022 15:35, Jonathan Corbet wrote:
> So this seems to be just a description of how email works

Well it felt appropriate to warn the user, because many people
(like myself before) might not realize this is happening even if
they think they know how email basically works.

> the Received headers always show the path through the net.

Yes, but is also dependent on the SMTP server configuration,
so someone might not realize that changing the server would
add such sensitive data to something public.

> Is this really something that we need to cover in the kernel docs?

It's part of the process, is it not? I'm sure many people
would like to have this information before starting on the
kernel for the first time.