Re: executable sendemail.smtpserver and b4 --reflect

From: Konstantin Ryabitsev <konstantin@linuxfoundation.org>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: icon@mricon.com, tools@linux.kernel.org, mjg59@srcf.ucam.org
Subject: Re: executable sendemail.smtpserver and b4 --reflect
Date: Wed, 12 Apr 2023 15:24:05 -0400	[thread overview]
Message-ID: <20230412-smokiness-portal-833f99@meerkat> (raw)
In-Reply-To: <CAKwvOdn6_J+9BppRbXEtDc8CW-qqoat7VJ521oWnqXCXHb_d6A@mail.gmail.com>

On Wed, Apr 12, 2023 at 12:00:09PM -0700, Nick Desaulniers wrote:
> $ b4 send --reflect
> 
> it seems that my series was sent to the list, surprisingly!
> https://lore.kernel.org/llvm/20230412-no_stackp-v1-0-46a69b507a4b@google.com/

Yes, this is bad, as the warning message specifically says that this won't
happen.

bugbot assign to me

> Internally at my employer, I must use a command line utility to send
> email outside of the blessed GUI.  As such, my ~/.gitconfig looks
> like:
> 
> ...
> [user]
>         name = Nick Desaulniers
>         email = ndesaulniers@google.com
> [sendemail]
>         from = Nick Desaulniers <ndesaulniers@google.com>
>         smtpserver = /usr/bin/sendgmr
> ...
> 
> From a discussion with you and Matthew on IRC, it sounds like this
> company-internal sendgmr utility might not be respecting some header
> b4 adds to the eml file (envelope-from?)?

What happens is that we expect that whatever we talk to will ignore the To/Cc
headers in the message and only send the message to the recipients specified
during the outer exchange (e.g. SMTP ignores anything in these headers and
only pays attention to the recipients passed in "RCPT TO"; the same is true
for actual "sendmail" command). 

The safe course of action is to bail on --reflect when we recognize that a
local executable is being used, because there is no guarantee that it will be
compatible with our expectations that To: and Cc: headers in the message will
be ignored.

> I can file a bug internally, but I'm not well versed on how to clarify
> precisely what's going wrong.  Is there anything to be done in b4
> itself, or help me word such a report I can file internally?

I'm not sure it's worth your effort for this particular case, as sendgmr
doesn't claim to be sendmail-compatible, it's a tool to use with
git-send-email and *deliberately* pays attention to To: and Cc: headers in the
message. To be sendmail-compatible, it would need to ignore To: and Cc:
headers in the message and only pay to recipients passed as command-line
arguments, unless -t is specified (e.g. see
https://man7.org/linux/man-pages/man8/sendmail.8.html).

> I also noticed that my name wasn't being sent on the From: field to
> LKML. I assume that's an orthogonal issue, but is there anything else
> I should be doing there?

Do you have "from = " set in your [sendemail] section?

-K