Re: dia-list Digest, Vol 193, Issue 9

[Olav Vitters <olav vitters nl>]

On Wed, Oct 21, 2020 at 01:22:04AM +0100, Zander Brown wrote:
> On Tue, 2020-10-20 at 20:04 -0400, Ron Wilson via dia-list wrote:
> > Adding a special header is not an option for most people. A topic specific
> > email address is something everyone can use.
> >
> > I have seen systems that accept a prefix or suffix to the user part of the
> > address for purposes of "sorting" incoming email into "sub folders" of the
> > user's mail box. The same idea could be adapted for tagging messages to
> > entered into Discourse (or other forum software).
>
> I believe the suggestion here was literally starting an email with
>
> Tagged: This, That, Whatever
>
> My message here

Upstream indeed proposed that. I don't think it's a good solution, it's 
a bit weird to write an email like that. Further, it'll likely lead to 
mistakes. For now (still loads of mailing lists to investigate) I don't 
think multiple tags will be used in an email address too often. And 
still, could have something like CATEGORY-TAG1,TAG2 gnome org, though 
something better than ",".

A solution could be a bit difficult, e.g. how to deal with someone 
sending one email to CATEGORY-TAG1 gnome org and cc 
CATEGORY-TAG2 gnome org. Still, it is better to handle the complexity in 
software rather than something that is likely to cause mistakes.

> Rather than messing around with message headers (as you say that would be quite
> inaccessible) though I must admit something like
> applications+dia discourse gnome org (vs the regular untagged
> applications discourse gnome org) makes more sense to me
>
> Of course this is something to mention/discuss upstream with Discourse

I think it was clear enough that they'd accept a patch. I'm hoping to 
find someone interested and capable. Seems it's written in Ruby on 
Rails, plus they support multiple methods for inbound email.

E.g. what I'd expect:
https://meta.discourse.org/t/straightforward-direct-delivery-incoming-mail/49487

But what they also support (polling via POP3):
https://meta.discourse.org/t/set-up-reply-via-email-support/14003

A quick search shows that it's likely the following file:
https://github.com/discourse/discourse/blob/a8d03e428ddf202e653d6e9496dc7e936635f2a7/lib/email/receiver.rb#L672-L679
this is called via an API (exactly how I'm not sure yet) via a docker 
mail-receiver. The Postfix configuration seems to be set here:
https://github.com/discourse/mail-receiver/blob/master/Dockerfile
Postfix currently passes on the entire recipient address.

Though not knowing Ruby, above file doesn't seem too complicated. It 
"just" needs to be expanded to support tags. Postfix puts the recipient 
extension (postfix in the environment variable EXTENSION (TAG in 
CATEGORY-TAG gnome org if 
http://www.postfix.org/postconf.5.html#recipient_delimiter is set to 
"-". Alternatively, the Postfix configuration can be adjusted. 
Interestingly, while this mail-receiver seems to check if there is a 
recipient, it doesn't pass this information on. See 
https://github.com/discourse/mail-receiver/blob/master/lib/mail_receiver/discourse_mail_receiver.rb. 
There it just seems to post the original email. It's a bit difficult to 
see what functions is called in between this file and the receiver.rb 
file (referred to earlier).

--
Regards,
Olav