Mirroring a read-only mailing list in Discourse

[Discourse]

This guide explains how to create a read-only mirror of a mailing list using Discourse. It covers the necessary site settings, category configuration, and subscription process.

Required user level: Administrator

Discourse can function as an archive for a mailing list while allowing registered users to utilize most of its features. This guide will walk you through the process of setting up your own mailing list mirror.

See this in our action on the Ruby-Talk mailing list mirror.

Summary

• Configure site settings for email handling
• Create or modify a category for the mailing list
• Subscribe to the mailing list
• Understand how the mirroring process works

The following guide uses two email addresses as placeholders. You need to replace them with your actual addresses.

discourse@example.com is address for incoming emails on your Discourse
mailing-list@foo.test is the submission address of the mailing list^[1]

Configuring site settings

1. If you’re not on a hosting plan that pre-configures incoming email, set up POP3 polling or manual polling via API for the account associated with your Discourse email address (e.g., discourse@example.com).

2. Enable the following site settings:

   • email_in: Allow incoming emails
   • enable_staged_users: Enable staged users (crucial for the mirroring process)

3. Optional settings:

   • Set authorized_extensions to * or add specific file extensions to allow the attachment types you need
   • Enable always_show_trimmed_content to allow all users to see trimmed content (hidden behind a button)
   • Enable display_name_on_posts and disable prioritize_username_in_ux for name display preferences

Creating or modifying a category

1. Create a new category or edit an existing one for the mailing list posts.

2. Configure category permissions:

   • Click the “Security” tab, then “Edit Permissions”
   • Remove all existing permissions
   • Add “everyone” with “See” permission
     
     

When you’re done, it should look like this:

3. Configure category settings:

   • Click the “Settings” tab
   • Enable “Accept emails from anonymous users with no accounts”
   • Set “Custom incoming email address” to the mailing list’s email address (e.g., mailing-list@foo.test)
   • Enable “Category mirrors mailing list”
     
     

4. Save the category settings.

Subscribing to the mailing list

1. Subscribe to the mailing list using your Discourse email address (e.g., discourse@example.com).

2. If the mailing list has a web interface, ensure the following settings:

   • Mail delivery is enabled
   • Digest mode is off
   • Password reminder emails are disabled

For Mailman 2, make sure:

• “Mail delivery” is “Enabled”
• “Set Digest Mode” is “Off”
• “Get password reminder email for this list?” is set to “No”

How it works

Enabling “Category mirrors a mailing list” changes how incoming emails are processed for that specific category:

• Auto-generated emails are allowed, even when block_auto_generated_emails is enabled
• All users can post via email, ignoring the email_in_min_trust setting
• Incoming emails use the Message-ID to find related posts, regardless of the find_related_post_with_key setting
• Markdown interpretation is limited to code blocks enclosed in triple backticks
• Rejection emails are not sent for mailing list posts

FAQs

Q: Can I mirror multiple mailing lists?
A: Yes, create a separate category for each mailing list and configure them as described above.

Q: Can users reply to notifications and post to the mailing list?
A: No, replies to notifications are sent to Discourse, not the original mailing list. Users cannot post directly to the mailing list through Discourse.

Q: How can I prevent users from posting to the mirrored category via email?
A: While the category allows email posting, you can keep the incoming email address private to prevent unauthorized posting.

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1. i.e. people send to this address to post to the list, and it also appears on the To:/CC: lines of emails sent by the list to members ↩︎

Last edited by @supermathie 2024-10-18T20:01:40Z

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