I wrote the post below in the moderators lounge on my site, and thought I’d share it here as potential faq material and to explore how others are using these features and the reasons why.
We have been brainstorming over the last several weeks (months?) about when to use personal messages, group inboxes and secure categories on discourse. Here’s a very brief breakdown which I hope will help clarify what is possible and which approach to use when. Happy to discuss and come to a shared understanding of when we use each of these, and update the info below as we move along.
Personal messages
What it is: similar to email but not private and with more limited functionality. Admins can (but don’t typically) read everyone’s messages. Functionality is nearly identical to discussion topics functionality, except you can address messages to specific usernames or group names (see below) and invite more people later once a message is already underway.
When to use it: Excellent and preferred alternative to email for directly contacting a member, for example to help them with a post. New members are automatically sent a personal message to welcome them to the community, as well as a weekly summary when they download resources. Messages are also a great way to have a one-off conversation with a number of people without burdening the rest of the community, for example to handle logistics for an event or plan a facilitated discussion.
Power tips: Personal messages can be a good first step to bringing people together on your own, before asking admins to create a discourse group and secure category (see below). As moderator, you can add and remove people to any message at will. You can also start a new message to the same people by using the icon. And finally, you can convert messages into discussion topics, and vice versa, and move one or more posts to an existing discussion topic.
Things to watch out for: It’s not possible for regular members to leave a personal message and it’s not possible for them to uninvite someone to a message after inviting them (this needs testing). It is possible for them to set the notification level to mute if a message gets too busy for their liking. Moderators can remove people from personal messages.
Group inbox
What it is: a goal of discourse software is to have near parity between discourse groups and discourse usernames. This means discourse groups can be configured to receive personal messages, just like members. Their messages are kept in a separate group inbox accessible to group members. Otherwise messages are identical to personal messages. As members are added and removed from a group, they gain and lose access to the group inbox.
When to use it: moderators have a group inbox so they can see personal messages sent to new members and to resource downloaders. This means we can use the whisper functionality to talk to fellow moderators about ways to engage these members, and then any of us can reply as appropriate. We are not using it for any other groups yet.
Power tips: Group inboxes can be set up with an email address, and it’s possible to turn on staged users functionality. This allows us to use discourse to correspond with people who are not yet members by email, while as a team also having the power of whispers, inviting more people, and other discourse features. If and when staged users join, they can then access their messages. It’s also possible to write a message to an email address, which creates a staged user and sends them an email. (Note: I tested this out with Ashley and it works very well and shows promise, but there are still some issues so don’t want to roll it out immediately.)
Things to watch out for: It is currently not possible to delete group inboxes except for admins to delete the group and recreate it (a fix for this is coming but don’t know when). When someone archives a group inbox message it affects everyone in the group. However, the read status is individual so group members can still see which group messages they have not yet read. Group members can set their own notification level for the group inbox, for example to be sent an email for every group message or only when their username is specifically mentioned.
Secure category
What it is: Categories are ongoing, long-term buckets for organizing and limiting access to discussion topics. Each topic can only be in one category (though can be in multiple tags). Secure categories are accessible only to certain discourse groups. Admins can see (but don’t typically look in) all categories. Otherwise, secure categories function identically to public categories. As members are added and removed from discourse groups, they gain and lose access to secure categories.
When to use it: We try to keep down the number of categories and avoid creating them for short-term purposes. Similarly, we try to keep down the number of discourse groups used for @ mentioning specific groups of people in discussions and to give access to private categories.
Things to watch out for: Because of the longer term strategic implications, consult with admins about creating groups and categories. We may decide to use a different method for engaging a specific grouping of people (e.g. personal messages). People also often get confused between categories and google groups/mailing lists/listservs, so the rollout of any new secure category has to be managed carefully.