I have built an Exchange 2013 CU8 on a dedicated VM. All servers are running Windows 2012 R2 and Exchange server is a member server in my local domain. I am able to send/receive email between users internally to my domain; however, I cannot send email to an external email recipient such as firstname.lastname@example.org. I have determined that my ISP (suddenlink) does block port 25. It looks like their SMTP server (smtp.suddenlink.net @188.8.131.52) must be used with authentication.
I don't how to configure Suddenlink's smtp server either into my Exchange server or if necessary on the Outlook client. Also, is there anything I need to configure on my router?