bug#14271: 24.3; MAILHOST set in mail-source.el when using pop3.el

[Katsumi Yamaoka]

Glenn Morris wrote:
> It might be simpler to let-bind process-environment?

Ah, thanks.

(shell-command-to-string "echo -n $MAILHOST")
 => ""

(let* ((server "mail.example.com")
       (process-environment (append (list (concat "MAILHOST=" server))
                                    process-environment)))
  (shell-command-to-string "echo -n $MAILHOST"))
 => "mail.example.com"

(let* ((server nil)
       (process-environment (append (list (concat "MAILHOST=" server))
                                    process-environment)))
  (shell-command-to-string "echo -n $MAILHOST"))
 => ""

I've done it in this way.