Yes, you can send bulk invites when using DiscourseConnect (WordPress SSO). Allowing invites to be sent when DiscourseConnect is enabled has changed a few times, so I’m testing it now to confirm that it works and also to check what the user experience is like.
Either sending invite emails via the Discourse UI, or uploading an invites CSV file causes emails to be sent without any issues.
When the user clicks the link in the invite email, they are taken to a screen that looks like this:
Clicking the Continue button redirects the user to the DiscourseConnect auth site (WordPress) for authentication.
For this test, I’m assuming that the invited user has not yet registered an account on WordPress, so they will need to click the Register link:
I’m testing this on a WordPress multi-site setup, so the registration form looks different than for a single-site setup:
From here, the user has to go through the process of confirming their email address with WordPress and then logging into WordPress. They can then login to Discourse, but the context of having initiated the process by accepting an invitation to the Discourse site is gone. They can go back to the Discourse site, click the Log In button and be logged into Discourse without any issues, but unless instructions were added to WordPress to guide the user, I think it would be very confusing.
So looking at this from a user’s point of view, it seems likely that when DiscourseConnect is enabled, inviting users who do not yet have accounts on the DiscourseConnect authentication site could be confusing. It works, but it would be more straightforward to invite users directly to the DiscourseConnect auth site, then display a link on that site that users can click to be logged into Discourse. Details for creating that link are here: Create a DiscourseConnect login link.
If the users already have accounts on the DiscourseConnect site, accepting invites to the Discourse site would be a straightforward process. But even for that case, it would probably be easier to just display a login link to Discourse on the DiscourseConnect site.