Implementing “right to disconnect” by delaying outgoing email?

France passed a law about “right to disconnect” (more info here or here). The idea of not sending professional emails when people are not supposed to read them in order to protect their private lifes, is a pretty good one, especially when hierarchy is involved. However, I tend to do email at random times, and I would rather continue doing that, but just delay the actual sending of the email to the appropriate time (e.g., when I do email in the evening, it would actually be sent the following morning at 9am).

I wonder how I could make this fit into my email workflow. I write email using mutt on my laptop, then push it locally to nullmailer, that then relays it,  over an SSH tunnel, to a remote server (running Exim4).

Of course the fallback solution would be to use mutt’s postponing feature. Or to draft the email in a text editor. But that’s not really nice, because it requires going back to the email at the appropriate time. I would like a solution where I would write the email, add a header (or maybe manually add a Date: header — in all cases that header should reflect the time the mail was sent, not the time it was written), send the email, and have nullmailer or the remote server queue it until the appropriate time is reached (e.g., delaying while “current_time < Date header in email”). I don’t want to do that for all emails: e.g. personal emails can go out immediately.

Any ideas on how to implement that? I’m attached to mutt and relaying using SSH, but not attached to nullmailer or exim4. Ideally the delaying would happen on my remote server, so that my laptop doesn’t need to be online at the appropriate time.

Update: mutt does not allow to set the Date: field manually (if you enable the edit_headers option and edit it manually, its value gets overwritten). I did not find the relevant code yet, but that behaviour is mentioned in that bug.

Update 2: ah, it’s this code in sendlib.c (and there’s no way to configure that behaviour):

 /* mutt_write_rfc822_header() only writes out a Date: header with
 * mode == 0, i.e. _not_ postponment; so write out one ourself */
 if (post)
   fprintf (msg->fp, "%s", mutt_make_date (buf, sizeof (buf)));