I checked that too! I looked @ there email field in both SPUser
profile as well as AD. We have ADFS setup so that it uses their email
address as there user name in SharePoint so they would not be able to get to
the task list if they did not have email set (they would not be able to
authenticate)
I looked at the link and the code, I am really thinking that this is
not the issue as for two reasons when the users come to the site anonymous
access is turned off so it forces them to login, if they did not have a
valid users name (which for the ADFS users is there email address passed)
then they would never get to the task list they would get the access denied
error as shown in the code. In my scenario they ALL (both AD and ADFS users
alike AND users that receive notifications and don't receive notifications
can get to the task list AND successfully creates a list item and assigns
them to a user, the issue arises at the notification process by SharePoint
for the users that it has been assigned to. Second reason is, this is an out
of the box task list not custom code used, I even created a new task list to
make sure it wasn't just the task list that had a corruption issue of some
sort but same results, that's why I am convinced that it is an issue with
the profiles or authentication/authorization process.
I think all of your logic is on the right path, I feel as if there is an
issue with the users profiles that have the tasks assigned to them that do
not receive the notification, but I have even gone as far as deleting the
profile and re-creating it. Not sure how familiar with ADFS you all are
(it's still a pretty big monster to me and I helped implement and configure
the servers/system) But you could think of it as similar to forms based
authentication, because it is just another secondary authentication
mechanism for SharePoint, hope that helps, Thanks for all your replies look
forward to more of your ideas/troubleshooting help. Also before I forget I
just tried a test assigning to a user that did not exist in either
authentication warehouse (AD and ADFS) and it created a new user profile for
Donald.Duck@... and not sure why that was allowed / happened any
thoughts on this may also led to an answer, also when I said earlier that I
deleted and re-create the user profiles this is how I did it, and I noted
that it assigned the new user profile with the same ID number as before,
could there be settings being store in the SP database that is either
corrupted and repeating itself?