I Can Send E-mail Locally But When I Try To Send It Externally It Won't. Why Is This?

One of the reasons that you can send email locally but when you try to send external email you do not have access on it. You might be using the intranet or the local area network on which there is a restriction on the people that they do not access the external environment for the security reasons. So when you use the lan it is controlled by the administrator all the clients have to take the permission in order to do any task for example if you want to send an email to other users your request with the server and then it allows the user to send an email to another users.

So it is centralized system which is controlled by the network administrator so you do not have access to send emails externally so you need to talk to your administrator in order to allow you to send external emails. Many people put restrictions on their network due to security reason so this is the one possible problem you might be facing due to the network security. So you can not send external emails.