Re: Default for the envelope From in smtpmail.el

[chad <yandros@MIT.EDU>]

On 12 Aug 2012, at 08:02, Stephen J. Turnbull <stephen@xemacs.org> wrote:

> chad writes:
>> I was hoping to clarify for Stephen that you guys aren't talking
>> about the same cases (at least, it seemed to me that you weren't).
> 
> That's true.  AFAICT I was talking about a superset of the cases that
> Glenn was, and that's important.

It's not a superset in the meaningful case; it's a subset - of the users.

> My basic point is that there are many different cases, and that Emacs
> (when acting as an MTA, which is more or less equivalent to speaking
> SMTP as it does via smtpmail.el) should try to make them all look the
> same to users.  That means that smtpmail.el should *default* to using
> the logged-in user's mailbox for the envelope sender.

This is a default that will be wrong the vast majority of the time. It
seems silly to choose to default to an assumption that stopped being
valid ~15 years ago instead of the value that the user already picked.

The cases where a user's login name on an emacs-capable machine is the
same as a workable email address are a small minority, even of emacs
users, and a fair chunk of those cases *could* use login-name, but
don't want to. Work addresses use a company server. School addresses
use a university server or service. ISPs, webmail, etc - none of them
use the user name.

Conversely, user-mail-address has been used for decades, and it
already documented to be exactly what we want:

	Specify your own email address, if Emacs can't figure it out
	correctly.
          (setq user-mail-address "cheney@torture.gov")

	Various Emacs packages, such as Message mode, consult
	user-mail-address when they need to know your email address. 
	See	Mail Headers.

If the user hasn't told emacs about an email address, then using the
login name is a reasonable choice. If the user *has* told emacs their
email address, emacs should use it.