The big pro with self-registration is that it doesn't need one of your people to sign them up.  So it can scale up much easier.   You then have the choice of manual approval (where one of your people approve the requests) of self-approval.  And with self-approval you can choose to have the system send the user an email to prove their are who they say they are.   Most spam systems drop suspect emails into the users spam folder.  So start by checking that.  If their spam system has outright dropped the email then there is nothing that user can do but ask someone at your company to manually approve them. ... View more