Are you able to debug from the other end? The admin of the mail server might have a clue what is happening here. If it failed to connect to the server a firewall might be the cause of the problem.
I want to point out a great tool, Papercut (opensource), you can install on your local client that acts as an SMTP server. It allows you to read all the emails you send out directly. The mail will not arrive at the destination, and it helps to develop email communication and test it fast. When setting up the Email Connector and it asks for a password, you can fill in any password, but you can not leave it empty.
It will help you to continue making your app and get the authorization details and protocols for your SMTP server from your admins later.
Go Make It