Cannot send email notifications to students
I'm working on migrating from an old Moodle system to a shiny new (self-hosted) Canvas installation. I have a lot of things working, including importing courses, users, and enrollments from our SIS. One thing that is not working is the sending of any email notifications to these new users.
I want to be clear here: email works generally; I am able to send notifications to other admins. Additionally, I'm not only talking about the initial setup or invitation messages; this is any email notifications to students at all.
As an admin, I can log into my new Canvas account and use the Inbox to create messages for other admins. The other admin accounts will receive email notifications about those messages, and are able to reply using both e-mail and their Canvas Inbox. If I do the same thing for a test student user login, I can login as that user in a separate browser and the message will be there in the canvas inbox, but no email notification is ever sent.
We have two primary accounts on this server (Site Admin, and one for "regular" institutional use), and I am listed as an admin on both of them.
I do see the correct email address for this user on their profile settings. It does show a star to indicate it is the default address, and there is no warning to confirm the address. I've been over the Notification settings, and I don't see anything wrong here. The correct email address also shows as the default address if I search for the test student user in the People section of that account as an admin.
I am also able to check the postfix mail logs on this server, and I can see the log entries there for the Canvas messages I sent to the other admins. But there are no postfix log entries, or even connection attempts, for the time periods where I've tried to send notices to the student.
Our admin accounts do have SIS_user_id values, but they were added later, so I'm not sure if the problem is because the users were first created by SIS, or because I'm missing some kind of role assignment, or if I'm missing something to mark the communication channel as confirmed. What could be going on here?