Re: message-send-mail-function, agent, and a day of work

[Kevin Greiner <kgreiner@xpediantsolutions.com>]

Wes Hardaker <wes@hardakers.net> writes:

> I spent way too much time the other day figuring out why my simple
> code to switch smtp servers was not working and all.  I was properly
> setting every variable I could find documented, but the effect seemed
> to be nothing.  The end result was because I was running with the
> agent turned on, I was missing a variable that is not documented with
> the rest of them (which makes some sense, as all the agents stuff is
> in one place).
>
> The problem is essentially this:
>
> 1) when you read about sending mail, the documentation says that the
>    variable 'message-send-mail-function is consulted to figure out how
>    to send mail.  This is what I was trying to modify.
>
> 2) However, the agent has his own variable for what to do when sending
>    anything:  gnus-agent-send-mail-function.
>
> The problem is twofold: first, there is no reference to the second
> variable in least a warning in the documentation related to sending
> mail.  Since the agent is turned on by default now, this will likely
> confuse a lot of people.  Second, the second variable is independent
> of the first.  This is part of the confusion.  I think the most simple
> solution would be to make the second variable point to a different
> function which checks the value of the first variable and uses that
> at runtime.  By default they both point at the same value, however, if
> the first one changes the second one never picks up that change in
> value.
>
> The gnus-agent-send-mail-function variable is set in gnus-agentize as
> follows:
>
>   (unless gnus-agent-send-mail-function
>     (setq gnus-agent-send-mail-function
> 	  (or message-send-mail-real-function
> 	      message-send-mail-function)
> 	  message-send-mail-real-function 'gnus-agent-send-mail))
>
> I'm suggesting this would be better:
>
>   (defun gnus-agent-use-current-send-mail-function ()
>          (funcall (or message-send-mail-real-function
>                       message-send-mail-function)))
>
>   (unless gnus-agent-send-mail-function
>     (setq gnus-agent-send-mail-function
>           'gnus-agent-use-current-send-mail-function))
>
> This way dynamic changes to the message-send-mail-function are picked
> up, but it still allows for customization of the agent specifically if
> desired.
>
> Thoughts?

The setq that assigns gnus-agent-send-mail-function must also assign
message-send-mail-real-function so that the mail functions will be
redirected to gnus-agent-send-mail.  Since you left that out, the
agent's ability to queue mail for later transmission is lost.  If we
simply restore the missing assignment, we get an infinite loop as
gnus-agent-send-function calls
gnus-agent-use-current-send-mail-function which funcalls
message-send-mail-real-function (i.e. gnus-agent-send-mail).

Your configuration shouldn't be changing
message-send-mail-real-function so
gnus-agent-use-current-send-mail-function could be re-written to just
funcall message-send-mail-function.

Hmmm.... This should work but it means that the agent will ignore the
initial value of message-send-mail-real-function.  Not at all sure if
that is the right thing to do.

(defun gnus-agent-use-current-send-mail-function ()
       (funcall message-send-mail-function))

(unless gnus-agent-send-mail-function
  (setq gnus-agent-send-mail-function   'gnus-agent-use-current-send-mail-function
        message-send-mail-real-function 'gnus-agent-send-mail))


Now, one question, are you writing your smtp switch logic into the
function called by message-send-mail-function?  I believe that you
must, if you want offline mail to also be send via multiple smtp
servers.

Kevin