Use the admin panel of your Discourse to configure this app.
### Configuring "Reply-By-Email"
* You should create a dedicated Yunohost user for Discourse whose mailbox will be used by the Discourse application. You can do this with `yunohost user create response`, for example. You should ensure that the email address is configured to be on your Discourse domain.
* You should then configure your Discourse `/var/www/discourse/config/discourse.conf` file with the correct SMTP configuration values. Please see [this comment](https://github.com/YunoHost-Apps/discourse_ynh/issues/2#issuecomment-409510325) for an explanation of what values to change. Please be aware, when you update the application, you will have to re-apply this configuration.
* You must enable the Pop3 configuration for Dovecot. See [this thread](https://forum.yunohost.org/t/how-to-enable-pop3-in-yunohost/1662/2) on how to do that. You can validate your configuration with `systemctl restart dovecot && dovecot -n`. Don't forget to open the ports you need (`995` is the default). You can validate that with `nmap -p 995 yunohostdomain.org`.
* You should then configure the Pop3 polling in the Discourse admin interface. Please see [this comment](https://meta.discourse.org/t/set-up-reply-via-email-support/14003) for how to do so. You will need to follow step 5 in that comment. You can specify your main Yunohost domain for the `pop3_polling_host`.
You should now be able to start testing. Try using the `/admin/email` "Send Test Email" and then view the "Sent" or "Skipped" etc. tabs. You should see a report on what happened with the email. You may also want to look in `/var/www/discourse/log/production.log` as well as `/var/www/mail.err`. You should perhaps also use [Rainloop](https://github.com/YunoHost-Apps/rainloop_ynh) or another Yunohost email client application to quickly test that both your user and the dedicated Yunohost Discourse user (`response@...`) is receiving mail.
### "Reply-By-Email" and mail forwarding
If you use the administration UI in YunoHost to setup a mail forwarding address for your users then you may face the problem whereby your users are replying by email from the forwarded email address and the Discourse software is not able to understand how to receive that email.
For example, your user has email address `foo@myyunohostdomain.org` and all mail is forwarded to `foo@theirexternalmail.com`. Discourse receives replies from `foo@theirexternalmail.com` but cannot understand how to deliver this to the user account with `foo@myyunohostdomain.org` configured.
Their is on-going work to allow for [multiple email addresses for one user](https://meta.discourse.org/t/additional-email-address-per-user-account-support/59847) in Discourse development but at current major version (2.3 as of 2019-08-06), there is no web interface for this functionality. It is possible to set it up via the command-line interface but it is **experimental** and you should not undertake this work unless you take some time to understand what it is you are going to do.
Here's how to setup a secondary mail address for a user account:
```bash
cd /var/www/discourse
RAILS_ENV=production /opt/rbenv/versions/2.7.1/bin/bundle exec rails c
