The student will normally report to the administrator that they are receiving emails from a course that they aren't enrolled in. After verifying that the student does not have an enrollment in the course (including disabled enrollments) the admin submits a support case.
This invalid data condition can be verified in the database by running the following queries:
Check the entries in USER_FORUM_SETTINGS:
(Note: the below query is only valid through SP14, as CONFERENCE_OWNER was dropped from the database schema starting with the April 2014 release.)
select ufs.pk1, u.user_id, cm.COURSE_ID, ufs.forum_role, ufs.SUBSCRIBED_IND, fm.name forum_name
from user_forum_settings ufs, forum_main fm, conference_main cfm, conference_owner co, users u, course_main cm
where ufs.USERS_PK1 = u.pk1
and ufs.FORUMMAIN_PK1 = fm.pk1
and fm.confmain_pk1 = cfm.pk1
and cfm.CONFERENCE_OWNER_PK1 = co.pk1
and co.OWNER_PK1 = cm.pk1
and users_pk1 = (select pk1 from users where user_id = 'USER_ID')
order by COURSE_ID;
Check the users's current enrollments:
select cu.pk1, u.user_id, cm.course_id
from course_users cu, course_main cm, users u
where cu.crsmain_pk1 = cm.pk1 and cu.users_pk1 = u.pk1
and cu.users_pk1 = (select pk1 from users where user_id = 'USER_ID')
If you are seeing courseIDs in the first set of results but not in the second set of the results, you are likely seeing this issue.
Once you have found the record in USER_FORUM_SETTINGS for which there is no enrollment, you can remove it from the database by using the following procedure:
IMPORTANT: Change the value above to the pk1 value of the USER_FORUM_SETTINGS record you want to delete.
This is known issue AS-150719 and is targeted for resolution in 9.1 SP5.