Re: Changing the default for `send-mail-function'

[Richard Stallman]

    However, one case described earlier (which is a common case) is that
    the bounce messages end up in root's mailbox (eg via the postmaster
    alias).  In that case, Emacs won't be able to read the mail.

Indeed it won't, but what is the situation where this occurs?
What causes it?

    There are many other reasons why the bounces won't end up where the
    user *can* find them, even if they (or Emacs) is looking for them.

What are some?

There is no inherent reason why local mail delivery of bounces should
be hard, so I think this indicates a bug or bugs in some software.

    This unreliability is unavoidable because mail is a store-and-forward
    channel, lacking a mandatory mechanism for confirmation of receipt by
    the addressee.  Neither the MTA nor the MUA can determine if the mail
    has failed for quite a while

That's true but it is a different question, not germane to this issue.
For this purpose, we don't need to tell whether any real message
succeeded in reaching its addressees.  We only need to tell whether
the local MTA has been configured and is meant to be used.

There is no fundamental reason why it should be hard to determine that.

Here's another approach to determining that:

1. Send mail to a nonexistent local address.
2. See if a bounce message arrives in your local mailbox in a reasonable time.
   If it doesn't, the MTA is not configured enough to deliver bounces.
3. Send mail to a remote address with a nonexistent host.
4. Look at the bounce message.
   The kind of error should tell you whether remote mail is configured.

However, the clean solution is to establish a conventional way for
programs to determine whether a machine has an MTA that should be
used.  sendmail should fail in a specific recognizable way when there
is not one.

-- 
Dr Richard Stallman
President, Free Software Foundation
51 Franklin St
Boston MA 02110
USA
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