They're all the same, right?

Client: I can't get into my email...
Tech: Ok. Is the page giving you any specific error messages?
Client: Well.. I keep trying to log on with the stuff I got in the mail from DDDDD University.
Tech: Ok, what is the page telling you when you try to log on?
Client: It says, "Email address does not exist, would you like to create one?"... Do I really have to fill out all this stuff? I've already been admitted to the university, why do I need to put in my name and email address?
Tech: That isn't an error message any of our pages currently give out. What website are you on?
Client: Yahoo Mail.
Tech: Why are you at Yahoo Mail?
Client: Well, obviously, I'm trying to log into my college email, but its not working because your system is broken...
Tech: You need to go to mail.DDDDD.edu to log into your university email.... not Yahoo Mail.
Client: But I like Yahoo Mail!
Tech: But to use your DDDDD University email, you can't access our systems by going to Yahoo Mail, you need to use the DDDDDD University email page.
Client: But.... they are all the same thing, right? They all go to the same thing, don't they?
Tech: No. Not at all. Our email and Yahoo Mail are two completely different things that go to two completely different systems.
Client: OH!! That's why I can't get logged in!!
Tech: Yes... You need to use the official DDDDDD University email page to access your mail.
Client: Ok, thanks!!!