Our developers have determined that the Enter/Return key issue you are seeing (where Enter/Return does not insert a new line in some cases) is due to a bug within certain versions of the Samsung Email application. We have contacted Samsung about this issue and they have provided a fix in more recent versions of their application. An updated email application that has this fix may be included as part of an overall system update for your device. For more detail on when to expect a system update, you can contact Samsung.
When you experience this bug, what happens is that Swype provides a call to the text editor (in this case the Samsung Email app) to make a new line. The email application is not respecting that call and no new line is entered. You will see that other applications where you can enter a new line will still work as expected. Swype is acting as expected, but the application does not input a new line.
It’s possible that some other keyboards may not have the issue you see with Swype, this is related to the method used to enter a new line. In Android, there are multiple ways to communicate this to the application. The method we use is not being respected by some versions of this application. In order to offer the best overall experience for our users, we are not able to change this behavior at this time. Samsung has already fixed this issue in newer versions of their Email application, and may distribute the updated version via a system update.