Trying to send out a task to an Android device fails with the error "-50 C2DM notification failed"
First seen in
Sophos Mobile Control 3.5
This error occurs if the connection from the Sophos Mobile Control server to Google's GCM servers is not possible
What To Do
Make sure your Sophos Mobile Control server is able to connect to the Google servers via the URL android.googleapis.com
Check your firewall if they are blocking access to this URL.
If your Android devices are connected to a Wireless LAN the following ports must be opened to enable GCM traffic: 5228, 5229 and 5230.