Hello Susyb1, I am glad to help out with this. There are several steps that we can take to correct the function of the application.
The first thing I would recommend you to do is to make sure you are on the latest version of the Xfinity Connect Application. You can check this by going to the Google Play Store, search for the Xfinity Connect app. The latest version of the application is 7.5.3.
If you are on the latest application version my next recommendation will be for you to go into your settings, click apps, then select the Xfinity Connect app. Once you select this you will then tap on storage and select clear data then tap ok at the bottom of your screen. Next, relaunch the application and attempt to send an email.
The steps that we took are in order to be able to launch the application as if we are doing so for the first time. Rest assured this will not delete any of your emails. You will be prompted to enter your user id and password upon launch. Please let me know if the recommended steps fixed the problem.