The question of how to mass email an announcement to all users on a Discourse site comes up fairly often. Discourse sites are not intended to be used as email sending services, but there are a couple of workarounds if you need to contact all of your site’s users.
Export the site’s users file and send emails from an external service
Click the “Export” link from the header of the Admin / Users page:
You will receive an onsite notification when the CSV export file is ready to be downloaded. Download the CSV file and open it in your favourite spreadsheet program. After extracting the values from the spreadsheet’s email column, upload the email addresses to an email sending service and send the emails from there.
Create a protected Announcements category on Discourse
Instead of sending the emails from an external service, you can create a protected “Announcements” category on Discourse and configure the category so that all users on the site are watching its first post by default.
It is important that you configure the category so that only a select group of users can create topics in it. For example, you could configure the category so that only site staff can create topics:
The reason for this is because in the next step, you will configure the category so that all users on your site are watching it by default. This will trigger an onsite notification for users who are active on the site at the time that new topics are created in the category, and will (by default) send an email to any of the site’s users who are not active on the site at the time the topic is created. It’s important to not spam your site’s users with emails, so only categories that limit topic creation to a select group of users should be configured for this.
To cause all new topics in the category to generate notifications or emails, add the category to your default categories watching first post setting:
After clicking the check mark button to save the setting, select the “Yes” option when you are asked if you would like to apply the changes historically:
Any new topics created in this category will trigger either an onsite notification or an email. Replies created in this category will not trigger emails or notifications unless users are specifically watching the topic.