(ah, I see you found this out for yourself while I was writing this but I will post it anyway)
I’ve always been fascinated by the possibilities of leveraging staged users to try to get engagement from people you know will never log in but who do respond to emails. For example, in the human rights and international development space there are so many thought leaders who are not interested in learning new platforms or who are just too busy to log in everywhere or read and follow up on email summaries from a bunch of forums. In the end I gave up and came to the conclusion that it’s not worth trying too hard because it is circumventing many of the intentions behind the discourse software platform, it’s an unsupported workaround, and can lead to some unexpected results.
Much better to use the invite system, which is supported and provides quite a bit of powerful functionality around inviting people and giving them access permissions to secure categories and sending them directly to a topic you want them to engage in. Setting up a full account is quick and easy for the invitee, and lets them participate more fully, directly via the platform.
That said, you can use the min trust to send email messages to limit who is allowed to use this feature. Set this to 4 (this is the default) and then don’t give that trust level to anyone except those you’d trust to start PMs to email addresses and create staged users. TL4 is near moderator level privs anyway so anyone with TL4 should already be a highly trusted member of your site.
There is also the allow changing staged user tracking admin setting which puportedly allows you as admin to manage the notification prefs of staged users. I haven’t tried it, but if this works as advertised, so you could create their staged accounts by PMing their email address and then editing the staged user’s notifications so they are watching categories or tags that you want them to receive email about and be able to reply to. Then you can even allow the staged user to start new topics by setting up the category email address and giving it to them.
