Just wanted to give back a little... the following relates to the same error message ("The system was unable to carry out the requested Action 'Create'") as discussed here, although not necessarily related to Outbound email issues.
Cause:
This occurrs if the user (RaiseUser) has no associated role with create permissions for the process (e.g., Incident). Our AD import of users was not followed up with any process to automatically associate a default role (e.g., PortalEndUser) with the new users, and led to this error being kicked back when creating an Incident with the user as RaiseUser either via email or in Webdesk.
Solution:
Lesson learned: make sure all of your users have at least one role as an End User or Analyst. Account Manager type roles might also work, but I can verify that Contact roles did not (at least not OOTB).
This is easy enough to check for by making a query in User Management under the appropriate User Type (e.g., End User). Choose whatever attributes you'd like to display and add the criteria "AND Roles.Creation Date Is NULL". You can then use this query (drag-n-drop) to add these users to a specific role via bulk action.
You can also use the following SQL statement to add a role automatically for the new users, although you will need to set it up as a scheduled task somewhere:
INSERT INTO tps_user_role (tps_user_id, tps_role_id, tps_creation_user_guid, tps_last_update_user_guid, tps_creation_date, tps_create_group_guid, tps_last_update, tps_update_group_guid)
SELECT tps_user.tps_guid, {GUID for role PortalEndUser}, {GUID for user System}, {GUID for user System}, CURRENT_TIMESTAMP, NULL, CURRENT_TIMESTAMP, Null
FROM tps_user
WHERE (tps_user.tps_guid NOT IN (select tps_user_id from tps_user_role)) AND (tps_user.tps_user_type_guid={GUID for user type End User})