Directing replies based on contents of To: header; was: How to match a string like '+447537170394 <sms at aa.net.uk>' in a send hook?

[Chris Green]

On Wed, Sep 25, 2024 at 12:43:36PM +0000, Michael Kjörling wrote:
> On 25 Sep 2024 12:11 +0100, from cl at isbd.net (Chris Green):
> >> So, next question (which replaces the first one), how can I change a
> >> To: header dependent on the contents of the To: header?
> >> 
> >> What I am trying to do is to change the destination address when I get
> >> messages from addresses like '+447537170394 <sms at aa.net.uk>' because
> >> messages back to that address disappear into a black hole.
> > 
> > To clarify, whhen I get an E-Mail with a From: header like:-
> > 
> >     From: +447537170394 <sms at aa.net.uk>
> > 
> > I want replies (i.e. the To: header) to go to:-
> > 
> >     To: Fred Bloggs <f.bloggs at another.address.co.uk>
> > 
> > I can't seem to get mutt to do this for me, I'm sure it must be
> > possible and, probably, quite easy.
> 
> Easiest is probably to inject a Reply-To: header in the original
> message based on whatever criteria you need. For example, if you're
> using procmail, try something like the following in your procmailrc:
> 
> :0
>  *^From: \+447537170394 <sms at sms\.example\.net>$
>   {
>   :0 fW
>     | formail -f -i "Reply-To: Fred Bloggs <f.bloggs at example.com>"
>   :0
>     $DEFAULT
>   }
> 
> The "fW" flags specifies that this rule is a "f"ilter (essentially
> re-injects the output of the pipe) and to "W"ait for the process to
> complete before continuing. The second rule delivers the message to
> the default mailbox which is where it would go in the absence of any
> matching filtering rule.
> 
> With formail -i (as opposed to -I), any existing similar header will
> be renamed with a -Old suffix. See the formail man page.
> 
> I have a number of similar rules in my setup and it works like a
> charm. The biggest caveat is that procmail operates on the _raw_
> message, so for example if the sender name may be surrounded by quotes
> or encoded somehow, you need to account for that.
> 
I'm not using procmail or anything similar, my mail is delivered
direct to my system by SMTP and I use postfix as my mail server.

I do have a custom python script, called from my .forward, that does
some procmail-like processing so I suppose I can add the header
changing code to that.

I'm surprised that there's no easy way to do it with mutt though.


-- 
Chris Green