When you are using the default OWA configuration you have to specify the "exchange" virtual directory in order to check your email. The URL looks like this: "httpss://mail.mydomain.com/exchange".
The following screencast demonstrates how to use the main URL: "httpss://mail.mydomain.com" by configuring a redirection to a URL.
I just finished the "Upgrade from Exchange 2007 to 2013" Part I screencast and must tell you that it is extremely well done! I found no variances between the video/script and what I experienced. At the end of Part 1 ...
Bob Duffett, Priority Software Inc. ...more...